Codon usage and base composition inRickettsia prowazekii |
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Authors: | Siv G E Andersson Paul M Sharp |
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Institution: | (1) Department of Molecular Biology, Biomedical Center, Uppsala University, S-751 24 Uppsala, Sweden;(2) Department of Genetics, University of Nottingham, Queens Medical Centre, NG7 2UH Nottingham, UK |
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Abstract: | Codon usage and base composition in sequences from the A + T-rich genome ofRickettsia prowazekii, a member of the alpha Proteobacteria, have been investigated. Synonymous codon usage patterns are roughly similar among
genes, even though the data set includes genes expected to be expressed at very different levels, indicating that translational
selection has been ineffective in this species. However, multivariate statistical analysis differentiates genes according
to their G + C contents at the first two codon positions. To study this variation, we have compared the amino acid composition
patterns of 21R. prowazekii proteins with that of a homologous set of proteins fromEscherichia coli. The analysis shows that individual genes have been affected by biased mutation rates to very different extents: genes encoding
proteins highly conserved among other species being the least affected. Overall, protein coding and intergenic spacer regions
have G + C content values of 32.5% and 21.4%, respectively. Extrapolation from these values suggests thatR. prowazekii has around 800 genes and that 60–70% of the genome may be coding.
Correspondence to: S.G.E. Andersson |
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Keywords: | Codon usage Mutation bias Rickettsia prowazekii |
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