Gene expression levels influence amino acid usage and evolutionary rates in endosymbiotic bacteria
2005
Schaber, J. | Rispe, Claude | Wernegreen, J. | Buness, A. | Delmotte, François, F. | Silva, F.J. | Moya, A. | Universitat de València = University of Valencia (UV) | Biologie des organismes et des populations appliquées à la protection des plantes (BIO3P) ; Institut National de la Recherche Agronomique (INRA)-Université de Rennes (UR)-AGROCAMPUS OUEST | The Josephine Bay Paul Center for comparative molecular biology and evolution | German Cancer Research Center - Deutsches Krebsforschungszentrum [Heidelberg] (DKFZ) | Unité Mixte de Recherche en Santé Végétale (INRA/ENITA) (UMRSV) ; Institut National de la Recherche Agronomique (INRA)-École Nationale d'Ingénieurs des Travaux Agricoles - Bordeaux (ENITAB)-Institut des Sciences de la Vigne et du Vin (ISVV) | Institut Cavanilles de Biodiverstitat i Biologia Evolutiva
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Afficher plus [+] Moins [-]anglais. Most endosymbiotic bacteria have extremely reduced genomes, accelerated evolutionary rates, and strong AT base compositional bias thought to reflect reduced efficacy of selection and increased mutational pressure. Here, we present a comparative study of evolutionary forces shaping five fully sequenced bacterial endosymbionts of insects. The results of this study were three-fold: (i) Stronger conservation of high expression genes at not just nonsynonymous, but also synonymous, sites. (ii) Variation in amino acid usage strongly correlates with GC content and expression level of genes. This pattern is largely explained by greater conservation of high expression genes, leading to their higher GC content. However, we also found indication of selection favoring GC-rich amino acids that contrasts with former studies. (iii) Although the specific nutritional requirements of the insect host are known to affect gene content of endosymbionts, we found no detectable influence on substitu! tion rates, amino acid usage, or codon usage of bacterial genes involved in host nutrition.
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