Vasudevan Pradeep, McElligott Jessica, Attkisson Christa, Betteken Michael, Popham David L
Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
J Bacteriol. 2009 Oct;191(19):6012-9. doi: 10.1128/JB.00604-09. Epub 2009 Jul 31.
Members of the COG2244 protein family are integral membrane proteins involved in synthesis of a variety of extracellular polymers. In several cases, these proteins have been suggested to move lipid-linked oligomers across the membrane or, in the case of Escherichia coli MviN, to flip the lipid II peptidoglycan precursor. Bacillus subtilis SpoVB was the first member of this family implicated in peptidoglycan synthesis and is required for spore cortex polymerization. Three other COG2244 members with high similarity to SpoVB are encoded within the B. subtilis genome. Mutant strains lacking any or all of these genes (yabM, ykvU, and ytgP) in addition to spoVB are viable and produce apparently normal peptidoglycan, indicating that their function is not essential in B. subtilis. Phenotypic changes associated with loss of two of these genes suggest that they function in peptidoglycan synthesis. Mutants lacking YtgP produce long cells and chains of cells, suggesting a role in cell division. Mutants lacking YabM exhibit sensitivity to moenomycin, an antibiotic that blocks peptidoglycan polymerization by class A penicillin-binding proteins. This result suggests that YabM may function in a previously observed alternate pathway for peptidoglycan strand synthesis.
COG2244蛋白家族成员是参与多种细胞外聚合物合成的整合膜蛋白。在一些情况下，这些蛋白被认为能将脂质连接的寡聚物转运过膜，或者就大肠杆菌MviN而言，能翻转脂质II肽聚糖前体。枯草芽孢杆菌SpoVB是该家族中首个被认为与肽聚糖合成有关的成员，是芽孢皮层聚合所必需的。枯草芽孢杆菌基因组中还编码了另外三个与SpoVB高度相似的COG2244成员。除了spoVB之外，缺失任何一个或所有这些基因（yabM、ykvU和ytgP）的突变菌株都能存活，并产生明显正常的肽聚糖，这表明它们的功能在枯草芽孢杆菌中并非必不可少。与缺失其中两个基因相关的表型变化表明它们在肽聚糖合成中发挥作用。缺失YtgP的突变体产生长细胞和细胞链，表明其在细胞分裂中起作用。缺失YabM的突变体对莫能菌素敏感，莫能菌素是一种通过A类青霉素结合蛋白阻断肽聚糖聚合的抗生素。这一结果表明，YabM可能在先前观察到的肽聚糖链合成的替代途径中发挥作用。
