Codon usage suggests that translational selection has a major impact on protein expression in trypanosomatids.


Horn, D; (2008) Codon usage suggests that translational selection has a major impact on protein expression in trypanosomatids. BMC Genomics, 9. p. 2. ISSN 1471-2164 DOI: https://doi.org/10.1186/1471-2164-9-2

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Abstract

BACKGROUND: Different proteins are required in widely different quantities to build a living cell. In most organisms, transcription control makes a major contribution to differential expression. This is not the case in trypanosomatids where most genes are transcribed at an equivalent rate within large polycistronic clusters. Thus, trypanosomatids must use post-transcriptional control mechanisms to balance gene expression requirements. RESULTS: Here, the evidence for translational selection, the enrichment of 'favoured' codons in more highly expressed genes, is explored. A set of highly expressed, tandem-repeated genes display codon bias in Trypanosoma cruzi, Trypanosoma brucei and Leishmania major. The tRNA complement reveals forty-five of the sixty-one possible anticodons indicating widespread use of 'wobble' tRNAs. Consistent with translational selection, cognate tRNA genes for favoured codons are over-represented. Importantly, codon usage (Codon Adaptation Index) correlates with predicted and observed expression level. In addition, relative codon bias is broadly conserved among syntenic genes from different trypanosomatids. CONCLUSION: Synonymous codon bias is correlated with tRNA gene copy number and with protein expression level in trypanosomatids. Taken together, the results suggest that translational selection is the dominant mechanism underlying the control of differential protein expression in these organisms. The findings reveal how trypanosomatids may compensate for a paucity of canonical Pol II promoters and subsequent widespread constitutive RNA polymerase II transcription.

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Pathogen Molecular Biology
Research Centre: Leishmaniasis Group
PubMed ID: 18173843
Web of Science ID: 252782300001
URI: http://researchonline.lshtm.ac.uk/id/eprint/8229

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