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Central Dogma of Genetics May Not Be So Central
Amorymeltzer writes "RNA molecules aren't always faithful reproductions of the genetic instructions contained within DNA, a new study shows (abstract). The finding seems to violate a tenet of genetics so fundamental that scientists call it the central dogma: DNA letters encode information, and RNA is made in DNA's likeness. The RNA then serves as a template to build proteins. But a study of RNA in white blood cells from 27 different people shows that, on average, each person has nearly 4,000 genes in which the RNA copies contain misspellings not found in DNA."
Who do you think they are, Soulskill, NERV?
Also, science holds no dogma. If it does, it ceases to be science.
We have known for many years that the same DNA codes to different proteins, with the adjustments given the information in the non-coding regions AND the information in the epigenome. That people have discovered that the intermediate step is also adjusted can hardly be called a shock. The proteins have to get built differently somehow, so some alteration in the intermediate coding was inevitable. Honestly! If geneticists aren't even reading their own bloody papers, maybe the government grants should be issued to those Slashdot readers who do.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
What it does in fact say is that information flows from DNA to RNA to proteins, and not the other way around: proteins can't write DNA.
This is not nearly as earth-shattering as the journo makes out.
When DNA is copied to make new DNA, you get a certain number of copying errors, called mutations - most of them harmless. I assume everyone knows about those.
When DNA is copied to make a temporary-working-copy RNA, you get a larger number of these copying errors because, in general, they are one-shot non-critical deals. The need for stringency is much lower, the selective advantage for stringency is not so great, so it comes as no surprise that the level of proof-reading is also reduced.
Now, it's also possible that there are mechanisms by which these RNA molecules can be purposefully edited. As mentioned in the article, significant post-transcriptional editing (including in eukaryotes the readaction of big chunks, which are called "Introns".) But this finding doesn't speak much to that, although the rate is a *sconch* higher than I might expect for random errors. Even so, this doesn't shake the central dogma of molecular biology in any meaningful way, as for example Reverse Transcriptases did.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
News for nerds who never took a biology course and are deeply suspicious of the so-called "sciences"
The summary and the abstract really say almost nothing other than to confirm that the misspellings aren't random and don't seem like lab artifacts.
I'd be interested to know how conservative these mistakes tend to be. If the mistakes generally replace amino acids with very similar ones it might be a programmed method of prodding just how much variation a structure can take while remaining functional. Weird and random events, which can be only so weird and so frequent before everything breaks entirely, are necessary for evolutionary adaptation, and these weird protein errors might be a previously unknown mechanism of exploring slightly different structures for proteins and seeing how far an organism can push the envelope.
Any engineer should find this to be perfectly intuitive. When the DNA itself replicates to produce a new cell entirely, there are a lot of extra safeguards to ensure as near-exact copying as possible, as mutations can easily be fatal. For RNA copying, there is no need for this sort of precision, because even if the resulting protein is useless, the cell remains alive, and a new RNA strand can easily be produced if needed.
"It is a good thing for an uneducated man to read books of quotations..." -Winston Churchill
(I so wanted to start the post that way)
No, the big thing about this (if indeed it holds up) is that the fidelity is much, much lower than expected. It doesn't seem that the mRNAs are miscoding (although it's possible) it seems that the coding is being jiggered with by other factors.
However, this is a statistical analysis of a number of genomes and the original genome coding teams warns that the precision of the decode may not be enough to warrant TFA's (tentative) conclusion.
But it's interesting and exciting. Stay tuned. Beats politics.
Faster! Faster! Faster would be better!
The amazing thing is not that there are mistakes, but the exact same mistakes occur in (almost) every strand of RNA! They aren't random errors, they occur the same way every time!
It seems likely that the earliest replicators (they may not even have been cells, per se) probably did not use RNA and DNA at all. RNA would have been a somewhat later innovation, like lipids being used to produce simple membranes to create a semi-permeable barrier to protect replication and protein synthesis. At that point we would have had simple cells.
The world's burning. Moped Jesus spotted on I50. Details at 11.
Yes, just random mistakes is why 10,000 "accidents" happen to the same exact gene exactly the same way in exactly the same spot every time, 100% of the time, in every cell their bodies, for multiple individuals. Random transcription error. Yes, you sure thought that one through. How embarrassing. No, but seriously, too bad you weren't on the peer review for the paper. You could have saved them from publishing such garbage!
ASCII stupid question, get a stupid ANSI
I for wun du not mind the speling erorz. So long as they kan reed it, wut difurinc duz it maek? Itz not liek thuh bodee iz a speling Notzee.
SSC
nearly 4,000 genes in which the RNA copies contain misspellings
I new my bad speling wasnt my falt- its just genetic. Finaly I can prove it to my teacher! I hope scientists next fined genes with bad grammar,
My webcomic
It's actually believed that the earliest forms of biochemical life consisted almost entirely of RNA. It is the only molecule we know of that can act as both information storage/transport and chemical catalyst (all proteins made by modern life are in fact polymerized by a reaction catalyzed by RNA). There is some disagreement as to whether this "RNA world" came before or after lipid membranes.
So here's a question.
Suppose that this "error" that happens every time nonetheless yields the same original DNA sequence?
dna half-strand ACTG ----> rna TATTCGAGATATAC ---> dna half-strand ACTG
It's been a very, very long time since I took my college biology, so be kind if I'm wrong. My point is that these might not be "errors" at all, just alternate intermediate steps that generate the same ultimate results. The assumption to date seems to be "one, and ONLY one, amino acid on RNA yields one, and ONLY one, corresponding amino acid on DNA". Is that necessarily the case, every time? I'm quite sure about ohhhh, a billion molecular biologists have already thought about this. I just don't know the answer.
Everybody gets what the majority deserves.
The fact that the "errors" are consistent, suggest this is not an error at all. There was a famous experiment utilizing genetic algorithms to build an optimal circuit with the least possible number of components. It was a simple circuit, and the optimal circuit was well understood. It was an attempt to prove that the genetic methodology would quickly yield this optimal circuit. To everyone's surprise, the process yielded a circuit with fewer parts than the theoretically optimal circuit. What the designers of the experiment hadn't taken into consideration was that the genetic algorithm didn't care about theory, only outcome. It had discovered a heretofore unknown capacitive reactance on the closely spaces lines of the experimental circuit board, and found a way to use that capacitance to reduce the number of parts in it's design. Given the nature of the system, evolution found a clever way to engineer around the believed limitations of the experiment, and utilize any and all real world resources to create a solution transcending of the point of view of the experimenters.
Likewise, there's something interesting going on here with the RNA, well outside of the obvious perspective of the researchers. Bring in biochemists, theoretical physicists, and maybe a couple applied organic chemical engineers. Let them figure out what's happening at the quantum and molecular level to have this outcome be the result. Start doing simulations. Look at topologies and protein folding.
Look at CJD (Creutzfeldt-Jakob Disease) or BSE (Bovine Spongiform Encephalopathy) the causative agent is a prion. A vital protein that in its normal state is essential to neurological function, which can fold in more that one way, and folded the wrong way destroys brain tissue and ultimately causes dementia and death. I'll bet dollars to donuts, that there is some funny quantum state, or a protein folding problem, or some simple nonbiological chemical process whose probable result is a code misspelling in protein formation. Its an interesting problem, but not at all surprising. We are complex systems, and trying to force the world processes that make us possible into a box is at once myopic and foolish.