The aim of this study is to investigate the process of cell division in mycobacteria since the factors involved in the control of cell division in mycobacteria are unknown. Undoubetdly, mycobacteria tuilize similar control networks and protein factors as other prokaryotes, but must employ additional or unique methods to control septation and division due to their unusual growth rate and cell wall composition. By screening DNA libraries from the slow growing species M. tuberculosis (Mtb) with a ftsZ gene fragment from a related actinomycete (S. coelicolor), we have identified and isolated a 4 kilobase DNA fragment containing ftsZ and subcloned the Mtb FtsZ coding sequence using the PCR. using similar methods, we have cloned the ftsZ gene from the fast growing species M. smegmatis. To date, these are the first genes encoding a primary cell division protein to be characterized in mycobacteria. Sequence analysis and comparison of both mycobacterial ftsZ genes reveals a 92% identify at the protein level with major differences in the c-terminal region only. Expression of these genes from heterologous promoters causes aberrant cell division and filamentation in E. coli. Preliminary experiments in the fast growing M. smegmatis species shows changes in colony morphology and growth characteristics when the ftsZ gene from Mtb is expressed in the cell. Experiments are underway to assess the phenotype of FtsZ overproduction in slow growing, virulent M. tuberculosis. Further genetic studies will involve the contruction of FtsZ hyper-expression mutants with the intention of creating mycobacteria minicells to be used as potential vaccine candidates.
