Abstract
AbstractAmong eubacteria and archeabacteria, amino acid composition is correlated with habitat temperatures. In particular, species living at high temperatures have proteins enriched in the amino acids E-R-K and depleted in D-N-Q-T-S-H-A. Here, we show that this bias is a proteome-wide effect in prokaryotes, and that the same trend is observed in fully sequenced mammals and chicken compared to cold-blooded vertebrates (Reptilia, Amphibia and fish). Thus, warm-blooded vertebrates likely experienced genome-wide weak positive selection on amino acid composition to increase protein thermostability.
Highlights
Evolutionary molecular biology is mostly concerned with the forces affecting individual genes
The ribosomal RNAs and transfer RNAs of prokaryotes living at high temperatures contain a much larger Guanine and Cytosine (GC)-fraction in their stem regions compared to prokaryotes living at more moderate temperatures, likely because G-C pairs are more stable to thermal fluctuations than A-T pairs
Despite large variation in amino acid composition within mesophiles (Fig. 1), we still see a significant correlation of ERK with optimal growth temperature among prokaryotes living at temperatures between 8°C and 50°C (Pearson’s R=0.23, p=0.0017; Spearman’s R=0.21, p=0.0045)
Summary
Evolutionary molecular biology is mostly concerned with the forces affecting individual genes. In the case of vertebrates, it was argued convincingly that the ‘isochore’ structure of high- and low-GC regions is not due to selection, but reflects varying fixation bias of GC over AT in the presence of recombination. A clear picture emerges only in the study of structured RNAs. The ribosomal RNAs and transfer RNAs of prokaryotes living at high temperatures contain a much larger GC-fraction in their stem regions compared to prokaryotes living at more moderate temperatures , likely because G-C pairs (with three hydrogen bonds) are more stable to thermal fluctuations than A-T pairs (with only two hydrogen bonds). In organisms living at elevated temperatures, RNAs that require a specific threedimensional structure to perform their function appear to be under selection for increased thermostability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
