title: Preference for guanosine at first codon position in highly expressed Escherichia coli genes. A relationship with translational efficiency.
abstract: The variation in base composition at the three codon sites in relation to gene expressivity, the latter estimated by the Codon Adaptation Index, has been studied in a sample of 1371 Escherichia coli genes. Correlation and regression analyses show that increasing expression levels are accompanied by higher frequencies of base G at first, of base A at second and of base C at third codon positions. However, correlation between expressivity and base compositional biases at each codon site was only significant and positive at first codon position. The preference for G-starting codons as gene expression level increases is discussed in terms of translational optimization.
authors.affiliation: Departamento de Genética, Universidad de Sevilla, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Gutiérrez
authors.forename: L
authors.initials: L
authors.lastname: Márquez
authors.forename: A
authors.initials: A
authors.lastname: Marín
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000737:chemistry; D001482:Base Composition; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005815:Genetic Code; D006151:Guanosine / Q000235:genetics*; D014176:Protein Biosynthesis; D016364:Reading Frames; D012044:Regression Analysis; D012641:Selection, Genetic; D018709:Statistics, Nonparametric
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D006151:Guanosine