The Unfolding of RecA
by MikeGeneIn my previous essay, I offered some support for viewing RecA as an evolution gene: it is ubiquitous, ancient, and plays a key role in the important and evolutionarily significant process of recombination. Also, the endosymbionts suggest that it can act like a switch when it comes to genomic integrity over time.
I've raised this all as an alternative perspective, where "RecA's functions are more fully realized across generations, something we would expect from an evolution gene." In other words, it's a question of observational scale. If, for some reason, we were restricted to making observations on the scale of milliseconds, we might be under the impression that RecA's function is to bind ATP, because the DNA repair functions of RecA are dependent on more time and other machinery. Thus, I'm raising a perspective that expands time even further, noting that DNA repair and recombination (what we measure in the lab) is part of the evolution-function of the gene (how an observer with a larger time frame might see it).
In my last essay, I mentioned that RecA was universal among free-living bacteria and that its amino acid sequence was strongly conserved. It's now time to consider another aspect.
August 24th, 2007 at 2:13 pm
Hi Mike,
Is the removal of Rad51B, Rad51C, Rad51D, DMC1, XRCC2, or XRCC3 as lethal as the removal of both copies of Rad51 from a mammal? As was the case with your example of the removal of Rad51 from a mouse.
Comment by Doug — August 24, 2007 @ 2:13 pm
August 24th, 2007 at 3:40 pm
Hi Doug,
(Hopefully Mike won't mind me butting in…)
Short answer: yes, for many of those genes, complete loss is embryonic lethal.
Long answer:
FYI, you can find that info for those or any other genes that catch your interest at the Mouse Genome Informatics database
http://www.informatics.jax.org
Enter the gene name in the search box (select Gene symbols/names in the drop down menu). You'll find that most of the Rad51-family genes have different symbols in the mouse genome, but a search with the old symbol that Mike used will pull them up.
Click on the gene symbol to go to the detailed page. Scroll down to "Phenotypes" If the gene has been knocked out, one or more alleles will be listed for "targeted" Sometimes there'll be a brief summary of the phenotype on the main page. If not, you can click through to details of phenotype.
Comment by Nick — August 24, 2007 @ 3:40 pm
August 24th, 2007 at 5:26 pm
Greatly appreciated, Nick!
Comment by Doug — August 24, 2007 @ 5:26 pm
August 24th, 2007 at 5:29 pm
Hi Nick,
Butt in any time you want. I think your long answer truly demonstrates what is great about the scientific community. You actually took a little of your time to help others learns how to gather information on their own. That was actually quite kind.
Comment by MikeGene — August 24, 2007 @ 5:29 pm
August 24th, 2007 at 5:32 pm
Hi Doug,
Since Nick answered your question, let me add a couple more things. The seven versions are not always crucial. Baker's yeast, a stream-lined unicellular fungus, only has four versions. And fruit flies and mosquitoes are missing at least one of them.
Comment by MikeGene — August 24, 2007 @ 5:32 pm
August 25th, 2007 at 9:56 am
Hi Doug,
One more thing. You asked, "Is the removal of Rad51B, Rad51C, Rad51D, DMC1, XRCC2, or XRCC3 as lethal as the removal of both copies of Rad51 from a mammal?" Notice that the telic hypothesis I raised has led you to raise a question that could easily be turned into a testable hypothesis. In fact, since I started speculating along these lines, both TP and Nick came up with their own testable hypotheses that would address some point along the way.
Comment by MikeGene — August 25, 2007 @ 9:56 am