Submitted to: Journal of Molecular Evolution
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/21/2003
Publication Date: 12/1/2003
Citation: Rooney, A.P. 2003. Selection for highly biased amino acid frequency in the TolA cell envelope protein of Proteobacteria. Journal of Molecular Evolution. 57(6):731-736. Interpretive Summary: The TolA protein helps bacteria survive under periods of stressful growth conditions. In addition, some antibiotics gain entry into the bacterial cell through TolA proteins. This study shows that TolA displays highly unusual evolutionary patterns that are correlated with bacterial ecology. The results of this study provide information on how TolA functions and evolves. This knowledge is important for the eradication of bacterial pathogens that threaten our food supply.
Technical Abstract: The bacterial cell envelope protein TolA functions to maintain the integrity of the cell membrane. This protein contains high levels of alanine and lysine that are used in the formation of alpha helices, which are required for normal protein function. The neutral model of molecular evolution predicts that amino acid composition and nucleotide composition are driven by the underlying GC content, as a result of mutation bias. However, this study shows that selection has acted to maintain high levels of alanine and lysine in the TolA protein of Proteobacteria, which in turn has biased nucleotide composition in the corresponding tolA gene.