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Why does the structure of RNA change?

Why does the structure of RNA change?


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RNA only has one strand, but like DNA, is made up of nucleotides. RNA strands are shorter than DNA strands. RNA sometimes forms a secondary double helix structure, but only intermittently. Why does RNA change structure? We see that DNA has a well-defined structure of a double helix. Why does RNA have to change it's own?

EDIT - My main focus is on this line "RNA sometimes forms a secondary double helix structure, but only intermittently."


Summary
Most nucleic acid species have specific structures (or a limited number of alternative structures) which may involve a greater or lesser amount of double helix through complementary base pairing. The extent of such helical components depends primarily on the availability of sequences of complementary bases, which is obviously greatest for the two distinct strands of a double-stranded DNA or RNA genome, but also occurs in a specific manner within RNA species where base-pairing has been evolutionarily conserved in particular regions.

Two ways of interpreting “why?”
When responding to questions about biomolecular processes and structure, I think it important to differentiate between two meanings of “why”, and I shall distinguish these by appropriate numbering in my answer.

1. The mechanistic “why”
This is generally easier to answer objectively, as it is request for a physico-chemical explanation for the formation of a structure (RNA or RNA in this case) or operation of a process.
It is worth emphasizing that just as different macromolecules of the class “protein” can adopt different particular structures - globular or fibrous with many variants on each - so can different RNA, and even DNA, species, as described below.

2. The functional “why”
By this I mean “what function(s) can a particular structure serve?”.
This is more difficult and beset with dangers. Whereas, we can say that the structure of myoglobin allows it to bind oxygen and release it as the partial pressure in tissues falls, with some macromolecules the function of their structural features may be less clear. The dangers here are in thinking that suggestions of function are facts, and that a particular function can only be accomplished or is best accomplished by a particular structure or structural feature.

The physico-chemical principles governing structure of macromolecules
Put simply, the structure adopted by a macromolecule in a particular environment is that in which it has the lowest thermodynamic energy (Gibbs Free Energy) in that environment. This is the structure in which the sum of the individual interaction energies (generally hydrogen bonds and Van der Walls interactions) is greatest.
Thus, a macromolecule is able to adopt alternative structures when these structures have similar energies, and the equilibrium between such structures can be changed by action of or interaction with other molecules.

Genomic DNA Structure(s)
Double-stranded DNA (dsDNA) genomes
1. Double-stranded genomic DNAs form an anti-parallel helical duplex structure (double-helix) primarily because they consist of two perfect complementary sequences that allow maximum hydrogen bonding of A-T and G-C base-pairs. The helical structure of the duplex allows the maximize the energetic π- π interactions of the stacked bases.
2. The function of genomic DNA is to maintain the genetic information of an organism and allow it to be transmitted to daughter cells. The double-stranded structure protects the bases from external modifying influences, to some extent, and allows the semi-conservative replication of the strands when a cell divides.
Single-stranded DNA (ssDNA) genomes
Some small viruses of bacteria and eukaryotes have single-stranded DNA genomes, illustrating that this particular function can be served by different structures.
1. Although the replication of ssDNA viruses involves production of a strand complementary to that of the genome, the genome is not double-helical - negating the generalization in the question. The simple reason for this is that the replication mechanism generates many more copies of the genomic DNA strand than the other: complementary nucleic acid sequences are required to form a double-helix! One could imagine a ssDNA having local regions that could base pair to one another, but this is prevented by the compact supercoiled structure that they adopt, which is a consequence of their closed-circular nature.
2. The compact super-coiled structure of such ss genomic DNAs (e.g. φX174) is suitable for encasing in a viral capsid (although ds circular viral genomes also supercoil).
The question of why some viruses have ssDNA genomes whereas most have ssDNA genomes is neither a mechanistic nor a functional “why”. It may be worth discussing, but falls into the realm of hypothesis.

Genomic RNA structures
1. To a large extent, the remarks above about the structure of genomic DNA apply to the genomic RNA of viruses. Genomes of dsRNA viruses have an anti-parallel helical duplex structure because two perfect complementary sequences are available in equal proportions from replication. Genomes of ssRNA viruses do not have this structure because replication generates primarily one type of strand. The ssRNA viruses, unlike the ssDNA viruses, have linear, rather than circular genomes.
2. I have nothing to say about the relation of these structures to function. Both are packaged into viral particles. Both can be replicated.

Transfer RNA (tRNA)
1. The single-strand of tRNA has a clover-leaf stem-loop structure with three short double-helical stems formed by Watson-Crick base pairing, folded into a three-dimensional L-shape by other hydrogen bonds. The sequence of bases in tRNA determines that this self hydrogen bonding can only occur in a manner to produce the particular structure.
2. The purpose of tRNA is to bring an amino acid onto the ribosome in response to a particular mRNA codon. The non-hydrogen bonded loop at one end of the folded molecule contains the anti-codon, allowing it to interact with a complementary mRNA codon; the free 3'-end at the other extremity is covalently attached to an appropriate amino acid. The compact hydrogen-bonded 'L' is of a shape that can be accommodated in the A or P site of the ribosome.

Ribosomal RNA (rRNA)
1. The single strands of the two major rRNAs are folded into a complex of stem-loops formed by short stretches of internal double helices involving either Watson-Crick (A-U, G-C) or single hydrogen-bond G-U base pairs. There is conservation of base pairs in the helical regions, without necessary conservation of particular bases. This determines that a specific structure is formed.
2. The double-helical stems are thought to play a structural role in the ribosome. The unpaired regions are free to interact with the various substrates of protein synthesis on the ribosome, and the catalytic centre is constituted of such unpaired bases. In this respect the ribosome represents catalytic RNA in which double-stranded regions have a functional role but the catalytic bases need to be unpaired.

Messenger RNA (mRNA)
1. mRNA is generally thought to lack hydrogen bonded secondary structure or have a limited amount of such structure, depending on the particular mRNA. This presumably reflects a general lack of complementary stretches of nucleotides in mRNAs. In eukaryotic mRNAs there is significant secondary structure at the 5' end in the untranslated region. Phage RNAs (and perhaps other mRNAs) do have significant double-stranded regions.
2. This can be rationalized as arising from the fact that the primary role of the bases in mRNA is to specify the sequence of a protein, and the mRNA must be capable of being translated by the ribosome. The secondary structure regions that do occur limit this, and may allow the control of translation. This latter point illustrates RNA flexibility - the potential for a switch from one structure to an alternative. This can only occur if the alternative becomes more energetically favourable, e.g. by unwinding of the helical region at the 5' end of eukaryotic mRNAs.'


Why does the structure of RNA change? - Biology

Ribonucleic acid or RNA is a nucleic acid polymer consisting of nucleotide monomers that plays several important roles in the processes that translate genetic information from deoxyribonucleic acid (DNA) into protein products

RNA acts as a messenger between DNA and the protein synthesis complexes known as ribosomes, forms vital portions of ribosomes, and acts as an essential carrier molecule for amino acids to be used in protein synthesis.

RNA is very similar to DNA, but differs in a few important structural details: RNA is single stranded, while DNA is double stranded.

Also, RNA nucleotides contain ribose sugars while DNA contains deoxyribose and RNA uses predominantly uracil instead of thymine present in DNA.

RNA is transcribed from DNA by enzymes called RNA polymerases and further processed by other enzymes.

RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins.

RNA is a polymer with a ribose and phosphate backbone and four different bases: adenine, guanine, cytosine, and uracil.

The first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine.

This base is also a pyrimidine and is very similar to thymine.

Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA.

In DNA, however, uracil is readily produced by chemical degradation of cytosine, so having thymine as the normal base makes detection and repair of such incipient mutations more efficient.

Thus, uracil is appropriate for RNA, where quantity is important but lifespan is not, whereas thymine is appropriate for DNA where maintaining sequence with high fidelity is more critical.


DNA Double-Helix Structure

Figure 2. DNA is an antiparallel double helix. The phosphate backbone (the curvy lines) is on the outside, and the bases are on the inside. Each base interacts with a base from the opposing strand. (credit: Jerome Walker/Dennis Myts)

DNA has a double-helix structure (Figure 2). The sugar and phosphate lie on the outside of the helix, forming the backbone of the DNA. The nitrogenous bases are stacked in the interior, like the steps of a staircase, in pairs the pairs are bound to each other by hydrogen bonds. Every base pair in the double helix is separated from the next base pair by 0.34 nm.

The two strands of the helix run in opposite directions, meaning that the 5′ carbon end of one strand will face the 3′ carbon end of its matching strand. (This is referred to as antiparallel orientation and is important to DNA replication and in many nucleic acid interactions.)

Only certain types of base pairing are allowed. For example, a certain purine can only pair with a certain pyrimidine. This means A can pair with T, and G can pair with C, as shown in Figure 3. This is known as the base complementary rule. In other words, the DNA strands are complementary to each other. If the sequence of one strand is AATTGGCC, the complementary strand would have the sequence TTAACCGG. During DNA replication, each strand is copied, resulting in a daughter DNA double helix containing one parental DNA strand and a newly synthesized strand.

Practice Question

Figure 3. In a double stranded DNA molecule, the two strands run antiparallel to one another so that one strand runs 5′ to 3′ and the other 3′ to 5′. The phosphate backbone is located on the outside, and the bases are in the middle. Adenine forms hydrogen bonds (or base pairs) with thymine, and guanine base pairs with cytosine.

A mutation occurs, and cytosine is replaced with adenine. What impact do you think this will have on the DNA structure?

Ribonucleic acid, or RNA, is mainly involved in the process of protein synthesis under the direction of DNA. RNA is usually single-stranded and is made of ribonucleotides that are linked by phosphodiester bonds. A ribonucleotide in the RNA chain contains ribose (the pentose sugar), one of the four nitrogenous bases (A, U, G, and C), and the phosphate group.

There are four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA). The first, mRNA, carries the message from DNA, which controls all of the cellular activities in a cell. If a cell requires a certain protein to be synthesized, the gene for this product is turned “on” and the messenger RNA is synthesized in the nucleus. The RNA base sequence is complementary to the coding sequence of the DNA from which it has been copied. However, in RNA, the base T is absent and U is present instead. If the DNA strand has a sequence AATTGCGC, the sequence of the complementary RNA is UUAACGCG. In the cytoplasm, the mRNA interacts with ribosomes and other cellular machinery (Figure 4).

Figure 4. A ribosome has two parts: a large subunit and a small subunit. The mRNA sits in between the two subunits. A tRNA molecule recognizes a codon on the mRNA, binds to it by complementary base pairing, and adds the correct amino acid to the growing peptide chain.

The mRNA is read in sets of three bases known as codons. Each codon codes for a single amino acid. In this way, the mRNA is read and the protein product is made. Ribosomal RNA (rRNA) is a major constituent of ribosomes on which the mRNA binds. The rRNA ensures the proper alignment of the mRNA and the ribosomes the rRNA of the ribosome also has an enzymatic activity (peptidyl transferase) and catalyzes the formation of the peptide bonds between two aligned amino acids. Transfer RNA (tRNA) is one of the smallest of the four types of RNA, usually 70–90 nucleotides long. It carries the correct amino acid to the site of protein synthesis. It is the base pairing between the tRNA and mRNA that allows for the correct amino acid to be inserted in the polypeptide chain. microRNAs are the smallest RNA molecules and their role involves the regulation of gene expression by interfering with the expression of certain mRNA messages.


RNA Structure

Patrick has been teaching AP Biology for 14 years and is the winner of multiple teaching awards.

RNA Structure is a single strand composed of nucleotides. Unlike DNA it does not form a double helix shape, but it does contain a series of nitrogenous bases (adenine, uracil, guanine and cytosine). RNA can temporarily form hydrogen bonds between bases of two strands.

When people think about nucleic acids, they typically think of DNA but there's another molecule RNA which is just as important. It's the one that takes the information that's being stored in DNA and sends it out to the cell so that the cell can actually use that info- information. DNA is a really long molecule RNA is typically a shorter molecule but it's just as important as DNA. It's the workers that help carry out some of the information and instructions of the DNA and it's built together much like DNA is so let's take a closer look.

The basic building blocks that make up RNA are nucleotides just like with DNA. Just like DNA it has a phosphate group then gives it a strong negative charge, it has a five carbon sugars sometimes called a pentose and some kind of nitrogen containing base or nitrogenous base. Now one of the differences to bear in mind between DNA and RNA is what is that pentose sugar. Well deoxyribose and ribose are the two sugars. Deoxyribose can you guess which one uses that? You're right! DNA which stands for Deoxyribose Nucleic Acid while RNA Ribonucleic acid uses ribose and if you look at the names they look very similar in fact if I cover up the deoxy I see the word ribose, what does that mean? Well this is ribose notice down here on the second carbon there's an OH group or hydroxyl group for those who are doing Chemistry. If I pull off that oxygen i.e. deduct it, then I deoxygenated this ribose here and look all that's left is the hydrogen so that's the difference between ribose and deoxyribose sugar.

The other difference that you'll see in the structure of the nucleotides is that it uses the same guanine and adenine and cytosine that DNA uses but instead of using thymine uses a particular kind of pyrimidine called uracil. Now to join RNA molecules together it works pretty much the same way as joining DNA molecules together. You take our phosphate and sugar and nitrogenous base i.e. a nucleotide and you bring the phosphate group of the next one in and it joins a phosphate to that sugar and then you extend that and so you windup with a long strand of RNA nucleotides with their bases sticking out with the phosphates and sugars forming the backbone of the strand.

Now you're familiar with this with DNA and you know that DNA often twist up to form the very famous double helix. Well RNA can't do that but because without addition oxygen that's on this carbon right there it tends to make it unstable for long stretches to be in a double helical form. For short portions however you can and the way you can form an RNA to RNA strand or RNA to DNA strand follows the same base pairing rules that DNA does with a lot of twist. Remember that RNA does not use thymine it uses uracil. DNA if we're binding DNA to RNA and we have a RNA adenine here this would have to be a thymine for DNA but if I was making an RNA to RNA where I have an adenine I'll have to use uracil which you'd abbreviate u so if I have my RNa strand here that's a, c, a I follow the standard base pairing rules of a to t or u, g to c so here's the c there's a guanine or g. Here's an a I put a thymine so that's it pretty straight forward it's much like DNA just with those little differences one mnemonic or trick to help you remember the key difference of using uracil instead of thymine is remember what's the abbreviation for uracil, it will be the letter u so just think in your head you are correct and if you are, you are correct.


Types of RNA

EQUINOX GRAPHICS / Science Photo Library / Getty Images

RNA molecules are produced in the nucleus of our cells and can also be found in the cytoplasm. The three primary types of RNA molecules are messenger RNA, transfer RNA and ribosomal RNA.

  • Messenger RNA (mRNA) plays an important role in the transcription of DNA. Transcription is the process in protein synthesis that involves copying the genetic information contained within DNA into an RNA message. During transcription, certain proteins called transcription factors unwind the DNA strand and allow the enzyme RNA polymerase to transcribe only a single strand of DNA. DNA contains the four nucleotide bases adenine (A), guanine (G), cytosine (C) and thymine (T) which are paired together (A-T and C-G). When RNA polymerase transcribes the DNA into a mRNA molecule, adenine pairs with uracil and cytosine pairs with guanine (A-U and C-G). At the end of transcription, mRNA is transported to the cytoplasm for the completion of protein synthesis.
  • Transfer RNA (tRNA) plays an important role in the translation portion of protein synthesis. Its job is to translate the message within the nucleotide sequences of mRNA into specific amino acid sequences. The amino acid sequences are joined together to form a protein. Transfer RNA is shaped like a clover leaf with three hairpin loops. It contains an amino acid attachment site on one end and a special section in the middle loop called the anticodon site. The anticodon recognizes a specific area on mRNA called a codon. A codon consists of three continuous nucleotide bases that code for an amino acid or signal the end of translation. Transfer RNA along with ribosomes read the mRNA codons and produce a polypeptide chain. The polypeptide chain undergoes several modifications before becoming a fully functioning protein.
  • Ribosomal RNA (rRNA) is a component of cell organelles called ribosomes. A ribosome consists of ribosomal proteins and rRNA. Ribosomes are typically composed of two subunits: a large subunit and a small subunit. Ribosomal subunits are synthesized in the nucleus by the nucleolus. Ribosomes contain a binding site for mRNA and two binding sites for tRNA located in the large ribosomal subunit. During translation, a small ribosomal subunit attaches to a mRNA molecule. At the same time, an initiator tRNA molecule recognizes and binds to a specific codon sequence on the same mRNA molecule. A large ribosomal subunit then joins the newly formed complex. Both ribosomal subunits travel along the mRNA molecule translating the codons on mRNA into a polypeptide chain as they go. Ribosomal RNA is responsible for creating the peptide bonds between the amino acids in the polypeptide chain. When a termination codon is reached on the mRNA molecule, the translation process ends. The polypeptide chain is released from the tRNA molecule and the ribosome splits back into large and small subunits.

Why an extra helix becomes a third wheel in cell biology

Every high school biology student knows the structure of DNA is a double helix, but after DNA is converted into RNA, parts of RNA also commonly fold into the same spiral staircase shape.

In a literal scientific twist, researchers are finding examples of a third strand that wraps itself around RNA like a snake, a structure rarely found in nature. Researchers recently have discovered evidence of a triple helix forming at the end of MALAT1, a strand of RNA that does not code for proteins. Yale postdoctoral fellow Jessica Brown and her colleagues working in the labs of Joan A. Steitz and Thomas A. Steitz describe the bonds that maintain the structure of a rare triple helix.

This extra strand of RNA, which is seen in the accompanying movie, prevents degradation of MALAT1. The formation of a triple helix explains how MALAT1 accumulates to very high levels in cancer cells, allowing MALAT1 to promote metastasis of lung cancer and likely other cancers.

The work is published in the journal Nature Structural and Molecular Biology.


The Structure of RNA

There is a second nucleic acid in all cells called ribonucleic acid, or RNA. Like DNA, RNA is a polymer of nucleotides. Each of the nucleotides in RNA is made up of a nitrogenous base, a five-carbon sugar, and a phosphate group. In the case of RNA, the five-carbon sugar is ribose, not deoxyribose. Ribose has a hydroxyl group at the 2′ carbon, unlike deoxyribose, which has only a hydrogen atom (Figure 4).

Figure 4: The difference between the ribose found in RNA and the deoxyribose found in DNA is that ribose has a hydroxyl group at the 2′ carbon

RNA nucleotides contain the nitrogenous bases adenine, cytosine, and guanine. However, they do not contain thymine, which is instead replaced by uracil, symbolized by a “U.” RNA exists as a single-stranded molecule rather than a double-stranded helix. Molecular biologists have named several kinds of RNA on the basis of their function. These include messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)—molecules that are involved in the production of proteins from the DNA code.


RNA Structure and Dynamics: The One-Two Punch in the Fight Against COVID-19

We are all well aware of COVID-19, and by now most people have seen pictures of the spike protein that forms the “handshake” interaction between virus and host cells and is the basis of two new vaccines. The COVID-19 virus is made of RNA, which manufactures the spike protein and all the other proteins that allow it to survive. What if scientists could target the RNA in the virus before that manufacturing process even begins? That’s where my work centers, around COVID-19’s viral RNA.

Before the proteins that infect your cells can be built, the viral RNA, which contains the blueprints to produce proteins essential for viral replication, must be read by the ribosome, the place where proteins are put together within a cell. Parts of the viral RNA form flexible structures that regulate the ability to read it and create proteins from it. If we can develop drugs that interfere with these RNA structures forming, the virus can’t function. In my work at the National Institute of Standards and Technology (NIST), I use computer simulations to predict what these RNA structures look like and how they move to gain a better understanding of how they can be targeted by drugs.

RNA structures are tricky to predict compared with protein structures for a few reasons. We have 3D maps of many more proteins (about 40 times more!) from all types of organisms, so algorithms to predict RNA structures start out with much less information about what they might look like. This is because RNA can be difficult to work with experimentally — so there are fewer tools available, at a higher cost, and generating data from experiments takes a long time. Also, RNA can be very flexible (aka “dynamic”), adding complexity to the prediction. Frequently, the same piece of RNA can form multiple structures, and we take them all into account to create an ensemble, a group viewed as a whole rather than as single, individual parts.

We are looking at RNA in a section of the COVID-19 viral genome that sets up translation, which is the process of reading the RNA to create the proteins the virus needs to survive. Specifically, two short regions called Stem Loop 2 and Stem Loop 3 (SL2 and SL3) contain important parts of the RNA that interact with other parts of the RNA to control the manufacture (expression) of proteins. They are called stem loops because the genetic sequence — repeats of the “letters” C, U, A, G — pair up C-G and A-U at the beginning and end of the sequence into a helix to form a ladder-like stem, while the middle part of the remaining sequence is unpaired in a loop. The RNA in SL2 has the same genetic sequence as the SL2 in the coronavirus SARS-CoV-1, the virus that caused severe acute respiratory syndrome (SARS) in the early 2000s.

So we hypothesized that the SL2 in the COVID-19 virus must adopt the same 3D structure found in the earlier SARS virus. However, computational predictions, which try to match sequences to parts of already determined RNA structures, generated 3D structures very different from the reported SARS-CoV-1 SL2 RNA. We wanted to find out if that would change using more advanced computational prediction.

Using all-atom molecular dynamics simulations, where we explicitly model the RNA, water and ions that would be present in the cellular environment, we find that the RNA rearranges quickly to match the RNA loop structure from SARS-CoV-1 with the same sequence. This shows that the all-atom molecular dynamics can adjust previous rough predictions that might not show the fine details of structure and resolve the dynamics of the RNA. And this means we can use it to predict details for something that we don’t have any other information on — a blind prediction.

For instance, SL3 is another short piece of the viral RNA that we think forms a loop. In many coronavirus genomes, there is something called a transcription regulatory leader sequence here. This transcription regulatory leader sequence helps to control protein expression. Some viruses have this piece of RNA unstructured, or flexible and able to adopt many different shapes, while other viruses, such as the one that causes COVID-19, are predicted to have this part of the RNA structured, or rigid and resistant to taking on different shapes. This RNA structure would also need to be easily disrupted for it to do its job and interact with other parts of RNA — making predicting its dynamics important if we are going to try and change them!

Simulations of SL3 show us that it is very flexible and adopts many different structures. Every so often, a potassium ion binds to SL3 and stabilizes a particular structure, creating a scaffold so the region we’re looking at can be recognized by RNA from further away. This allows for the RNA in this region to have enough structure to trigger reading, while making it easy enough to eliminate structure so the reading can smoothly progress. You can imagine it as a draw bridge, which needs to be down for cars to pass over it and up for boats to pass under it — like the SL3 RNA, both orientations are essential to its job.

We know that the computer simulations that we use result in models that are accurate because they are close to structures that we have actually seen in lab experiments. By having confidence in the computer simulation methods, we can extend them to other parts of the RNA. The SL3 computational prediction links the RNA structure to known function for how transcription is controlled. Using molecular dynamics to link and predict structure and function is the goal of these computational methods.

Predicting RNA structure is also important for developing drugs and vaccines where the RNA is itself the “active ingredient,” as in the Pfizer and Moderna COVID-19 vaccines. In these vaccines, the RNA needs to interact with other “ingredients” to come together in a formulation that can get the RNA into cells in the right amount of time, allowing its code to be read by cellular machinery, while remaining stable in vials in the clinic at reasonable temperatures. By understanding structure and function, we can engineer stability into drug products, optimizing for downstream manufacturing concerns such as avoiding extremely cold storage temperatures, for example.

We are using computer simulations and all-atom molecular dynamics to predict how these pieces interact and how we can change the ingredients to help make stable vaccines. This expands work done under the NIST Biomanufacturing Initiative, a program that to date has largely focused on measurements and standards to support development of protein-based drugs, to RNA-based drug platforms. Given the technical challenges, cost and time required for exploratory experimental work in the development of RNA-based drug platforms, application of fast computational algorithms to perform the biophysical characterization that is central to our work at NIST can be used to save stakeholders time and money, and to help expedite bringing these life-saving drugs to the public.


Data availability

The structures generated during the current study have been deposited in the Worldwide Protein Data Bank under accession codes 6R9I (apo), 6R9J (A7-bound), 6R9M (AAGGAA-bound), 6R9O (AAGGA-bound), 6R9P (AAUUAA-bound) and 6R9Q (AACCAA-bound). Source data for Figs. 1b–e, 2b–d, 4c, 5a and 7b and Supplementary Figs. 1e,f, 2a, 6e–g and 7a,b are available in tabular form with the paper online. Source data for Figs. 1a, 2a and 6a–h are available in Supplementary Dataset 1 with the paper online. All annotated gels are available on Mendeley (https://doi.org/10.17632/zkfsh9nftk.1). All other data that support the findings of this study are available from the corresponding author upon reasonable request.


Octopuses and squids can rewrite their RNA. Is that why they’re so smart?

When Inky the octopus escaped from his tank at New Zealand’s National Aquarium in April 2016, he squirmed through a six-inch-wide drainpipe and stole away into the Pacific. He stole more than a few human hearts along the way, too. Inky fans celebrated the animal that outwitted the aquarium: “Please watch out — he is heavily armed,” one commentator quipped.

The intelligence of octopuses goes far beyond escape artistry. They can unscrew glass jars from the inside and solve other complex mechanical problems. They play. Some are capable of body-contorting mimicry. All of this is to say that cephalopods — the spineless, many-legged creatures including octopuses and cuttlefish — stand out among their fellow mollusks. Pity in comparison the oyster, a mollusk that, sadly, doesn't even have a proper brain.

Cephalopods are unusual not only because they solve puzzles and clams cannot. Squids, cuttlefish and octopuses do not follow the normal rules of genetic information, according to research published Thursday in the journal Cell. Their RNA is extensively rewritten, particularly the codes for proteins found in the animals' neurons.


Watch the video: DNA Translation. mRNA to Protein, and tRNAs Role (November 2022).