| The genus Bartonella contains several species that are emerging pathogens of clinical significance, including Bartonella bacilliformis, a human pathogen endemic to the high altitude valleys of the Andes, B. henselae, the causative agent of Cat Scratch Disease, and B. quintana, the pathogen responsible for urban trench fever. These three species were previously found to contain a set of genes that were homologous to genes located in the dcw cluster of E. coli. The dcw cluster is conserved across bacterial species and contains several genes whose products are essential for cell division.; Further characterization of the dcw cluster of B. bacilliformis resulted in the isolation of a gene coding for a homologue of FtsW, a protein that has been shown to be essential for cell division in E. coli. Thefts W genes from B. bacilliformis , B. henselae and B. quintana were isolated, sequenced, and introduced into expression vectors for production of the gene products. Genes coding for homologues of two other essential cell division proteins, FtsI and FtsK, were also isolated from a B. bacilliformis genomic library and characterized.; The topology of B. bacilliformis FtsW was investigated using translational fusions of segments of thefts W open reading frame to phoA, lacZ, and ECFP. The results suggest the existence of six membrane-spanning domains, two large periplasmic regions, and a large C-terminal cytoplasmic tail.; The mechanism used by B. bacilliformis to bring about cell division was investigated by analyzing the protein-protein interactions among six cell division proteins with a yeast two-hybrid system. Fourteen fusions containing all or parts of B. bacilliformis protein coding sequences were constructed. Interactions at medium/high levels of stringency were observed between the N-terminal halves of FtsZ (FtsZ-N) and FtsZ-N, FtsW, FtsI, and FtsA, and between FtsW with FtsI. In addition, interactions were detected between the C-terminal half of FtsZ and FtsA. The site of interaction with FtsZ was localized to the N-terminal 80 amino acids of FtsW through the use of fusions containing defined regions of the ftsW open reading frame. Based on these studies, a model is presented that localizes FtsQ, FtsI, FtsW, and FtsA with respect to the FtsZ ring and the inner membrane of the cell. |
