Nucleotide sequence of the Caulobacter crescents flaF and flbt genes and analysis of codon usage in organisms with G+C-rich genomes

The Caulobacter crescentus flaFG region encodes trans-acting, regulatory factors that modulates flagellin synthesis during flagellum biogenesis. In this study, sequence analysis and experiments utilizing a promoterless cat gene demonstrated that the flaF and flbT genes have overlapping transcripts with the same orientation. In addition, the 5′ ends of the flgL and flbA genes were located. A sequence resembling an Rho-factor-independent terminator was found in the 3′ region of the flaF gene. This region was uniquely A + T-rich and the encoded mRNA contained an inverted repeat sequence which could form a stable stem-loop strucuture followed by nine U-residues. The codon usage of C. crescentus genes was examined and indicated a preference for specific codons from each of the synonymous codon groups. Furthermore, comparison to the codon usage of other organisms with G + C-rich genomes indicated a strong preference for the same codons prefered by C. crescentus.