Functional Characterization of the Cell Division Gene Cluster of the Wall-less Bacterium .

It is well-established that FtsZ drives peptidoglycan synthesis at the division site in walled bacteria. However, the function and conservation of FtsZ in wall-less prokaryotes such as mycoplasmas are less clear. In the genome-reduced bacterium , the cell division gene cluster is limited to four genes: , , MG_223, and . In a previous study, we demonstrated that was dispensable for growth of under laboratory culture conditions. Herein, we show that the entire cell division gene cluster of is non-essential for growth . Our analyses indicate that loss of the gene alone is more detrimental for growth of than deletion of or the entire cell division gene cluster. Transcriptional analysis revealed a marked upregulation of in the mutant. Stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics confirmed the overexpression of FtsZ in MraZ-deprived cells. Of note, we found that expression was upregulated in non-adherent cells of , which arise spontaneously at relatively high rates. Single cell analysis using fluorescent markers showed that FtsZ localization varied throughout the cell cycle of in a coordinated manner with the chromosome and the terminal organelle (TMO). In addition, our results indicate a possible role for the RNA methyltransferase MraW in the regulation of FtsZ expression at the post-transcriptional level. Altogether, this study provides an extensive characterization of the cell division gene cluster of and demonstrates the existence of regulatory elements controlling FtsZ expression at the temporal and spatial level in mycoplasmas.