Pseudogene rescue: an adaptive mechanism of codon reassignment.
Alterations to the genetic code--codon reassignments--have occurred many times in life's history, despite the fact that genomes are coadapted to their genetic codes and therefore alterations are likely to be maladaptive. A potential mechanism for adaptive codon reassignment, which could trigger either a temporary period of codon ambiguity or a permanent genetic code change, is the reactivation of a pseudogene by a nonsense suppressor mutant transfer RNA. I examine the population genetics of each stage of this process and find that pseudogene rescue is plausible and also readily explains some features of extant variability in genetic codes.
Johnson
L J
LJ
School of Biological Sciences, University of Reading, Reading, UK. L.J.Johnson@Reading.ac.uk
D000222:Adaptation, Physiological / Q000235:genetics*; D003062:Codon / Q000235:genetics*; D014644:Genetic Variation; D008957:Models, Genetic; D011544:Pseudogenes / Q000235:genetics*
D003062:Codon