They found that “genes with a greater proportion of third-position Gs or Cs are expressed more than genes with third-position As or Us”.
Click here for a synopsis of the paper.
There were other “emergent” features in genes whose GC3 was high. Some showed an increase in immunogenicity, other an increase in mRNA lifetime, and a high GC3 retrotransposon showed higher retrotransposition activity than its low GC3 counterparts.
Wow! I find it enthralling. The problem is that no evolutionary clues are given for such behaviour.
Why an increase in mRNA for GCs in the third position particularly?. I would like to know first of all if the same is found for genes where the synonymous mutations, or even mutations whose change in aminoacid don´t compromise the gene´s function, affect other than the third position.
I think it might have to do with affinity of the polymerase for the strand. I never thought of it, but does RNApol have the same affinity for all the genes? I know that the sigma factor is directly involved in promoter recognition, but what about the rest of the gene?
I hope much more is to come about this fine gene-tuning!