Characterization of dnaA gene expression in Mycoplasma capricolum

Expression of the dnaA gene in Mycoplasma capricolum was studied. The transcriptional start site was located 10 bp upstream from the putative translational initiation codon. Immunoblotting analysis revealed that DnaA protein was expressed at the levels significantly larger than those in Escherichia coli, and was localized mainly in the membrane. The transcriptional level of dnaA gene was reduced by inhibition of DNA synthesis with methyl methanesulfonate or mitomycin C, while the level of DnaA protein did not change. Reduction of protein synthesis did not significantly affect the total amount of DnaA protein, suggesting that the rates of synthesis and degradation of the protein are slow. These observations showed that the expression pattern of dnaA gene in M. capricolum is different from those of walled bacteria in some aspects.