Poster #RP206
Computational identification and analysis of paralogous gene families encoding α-helical transmembrane proteins in two complete bacterial genomes
Vasilis Promponas*, Ourania Limitsiou**
*Bioinformatics Research Laboratory, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus; **Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Athens, Greece
In this work we have tried to investigate the conservation rates of predicted α-helical transmembrane (αTM) proteins in two complete bacterial genomes (Escherichia coli K12, Chlamydia trachomatis) encoded by paralogous genes. Taking BLASTP %identities as a measure of sequence conservation, we have shown that, in general, paralogs in E. coli are significantly more conserved than those in C. trachomatis (42.6% versus 33.5%; Mann-Whitney test: W=298132, p=7.8e-5). Surprisingly, when only the αTM protein subsets were examined, no remarkable differences were detected. We also compared paralogous pairs of αTM against non-αTM proteins in both genomes, detecting significant differences only on those encoded in the E. coli genome (29.7% vs 33.5%; W=2347680, p<2.2e-16). The same kind of analysis revealed that αTM orthologs are less conserved than non-αTM ones (27.0% versus 31.3%; W=11672, p=2.3e-13).
Our analysis reveals that, in general, paralogs are more conserved in the E. coli genome, suggesting recent duplication events. Specifically, paralogs encoding αTM proteins seem to evolve significantly faster, probably due to weaker evolutionary pressure in transmembrane α-helices.