Net Evolutionary Loss of Residue Polarity in Drosophilid Protein Cores Indicates Ongoing Optimization of Amino Acid Composition.

ABSTRACT: Amino acid frequencies in proteins may not be at equilibrium. We consider two possible explanations for the nonzero net residue fluxes in drosophilid proteins. First, protein interiors may have a suboptimal residue composition and be under a selective pressure favoring stability, that is, leading to the loss of polar (and the gain of large) amino acids. One would then expect stronger net fluxes on the protein interior than at the exposed sites. Alternatively, if most of the polarity loss occurs at the exposed sites and the selective constraint on amino acid composition at such sites decreases over time, net loss of polarity may be neutral and caused by disproportionally high occurrence of polar residues at exposed, least constrained sites. We estimated net evolutionary fluxes of residue po

SUBMITTER: Yampolsky LY 

PROVIDER: S-EPMC5737390 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature