The ICR does not usually post on local public holidays, but for Veterans Day (November 11) we have Incredible Microprocessor Protein Acts as Genome Guardian from Jeffrey Tomkins:
Researchers recently studied a highly sophisticated cellular machine that acts as a guard for the genome against harmful mutations and that evolution cannot explain.
Grammar is a wonderful thing – does he mean that “evolution cannot explain” the protein or the mutations? I don’t know for certain, but we’re going to have to use the former as our working assumption.
There are actually a number of proteins involved here: first are Drosha and Pasha. Drosha is a Class 2 RNase III enzyme which cleaves strands of pri-miRNA into pre-miRNA as the first step in turning it into miRNA (micro-RNA) proper. Pasha, known in vertebrates as DGCR8 due to its association with DiGeorge syndrome, binds double-stranded RNA, aiding Drosha’s job – the two proteins bind together to produce the miRNA processing “Microprocessor” (why this gets a capital letter I don’t know – Tomkins isn’t using it, but everyone else is). The next step in miRNA processing is preformed by a third protein called Dicer – which dices up the pre-miRNA, of course – but this appears to be beyond what we need to know today.
That brings us to the paper, The Microprocessor controls the activity of mammalian retrotransposons, published online on the 1st of September and in print in Nature Structural and Molecular Biology in October. Retrotransposons (or transposable elements, transposons etc) make up 40% to 50% of the human genome – they are sequences which copy themselves across the genome, leaving numerous dead and decayed versions of themselves behind for seemingly no purpose beyond their own replication. Jeffrey Tomkins thinks that they are all functional (same as the rest of the genome, in his mind) but only has a few specific examples to back himself up. After all, if half the genome is made up of the remains of repeated sequences that once had the ability to be transcribed and then turned back into DNA there’s plenty of raw material available from which useful function could be moulded by evolution. 50% of the genome isn’t going to be biologically inert, but it should also be a bit busier if it is truly 100% functional.
Accumulation of transposons at too great of a rate is not likely to be a good thing for an organism, as just randomly inserting sequences is going to muck up where the important stuff is, so it would make sense to predict the existence of systems to mitigate their spread. To cut a very long story short, it turns out that the Microprocessor is capable of not just cleaving pri-miRNA to make pre-miRNA, but also cleaving the mRNA that makes a protein important to the copying of certain retrotransposons in some way that is not yet fully understood. This makes it harder for the affected transposons to proliferate, which is a Good Thing.
Now, if you remember from the beginning of the article (or just scroll up a bit), we were promised something that “evolution cannot explain.” Tomkins wasn’t all that clear about what that was going to be, but the implication by now is that it’s the Microprocessor. He actually spends most of the article briefly explaining what the Microprocessor does, and also insisting that retrotransposons are beneficial and useful as we already mentioned even though in this case they are quite the opposite, which leaves his one-sentence conclusion to do the job for him. It asserts simply:
With such a multi-purpose and highly specific function, it is clear that the incredibly engineered microprocessors show powerful design features that are critical to life and good health and that cannot be explained by random evolutionary processes.
It would appear as if Tomkins is arguing that the observation that a protein that does a certain thing to one kind of RNA also does the same thing to a different kind for a different purpose is the “highly specific” design of God, and that evolution couldn’t accomplish the same end result. Why? Because he said so, and he definitely wouldn’t say something he couldn’t back up with hard evidence.
Enjoy your 11/11 – or whatever it is you’re supposed to do on that day.
I got annoyed with a press release in one of my RSS feeds and made a tumblr. Anyone else got one?