de Boer P A, Crossley R E, Hand A R, Rothfield L I
Department of Microbiology, University of Connecticut Health Center, Farmington 06030.
EMBO J. 1991 Dec;10(13):4371-80. doi: 10.1002/j.1460-2075.1991.tb05015.x.
The proper placement of the cell division site in Escherichia coli requires the site-specific inactivation of potential division sites at the cell poles in a process that is mediated by the MinC, MinD and MinE proteins. During the normal division cycle MinD plays two roles. It activates the MinC-dependent mechanism that is responsible for the inactivation of potential division sites and it also renders the division inhibition system sensitive to the topological specificity factor MinE. MinE suppresses the division block at the normal division site at mid-cell but not all cell poles, thereby ensuring the normal division pattern. In this study the MinD protein was purified to homogeneity and shown to bind ATP and to have ATPase activity. When the putative ATP binding domain of MinD was altered by site-directed mutagenesis, the mutant protein was no longer able to activate the MinC-dependent division inhibition system. Immunoelectron microscopy showed that MinD was located in the inner membrane region of the cell envelope. These results show that MinD is a membrane ATPase and suggest that the ATPase activity plays an essential role in the functions of the MinD protein during the normal division process.
在大肠杆菌中，细胞分裂位点的正确定位需要在一个由MinC、MinD和MinE蛋白介导的过程中，对细胞两极潜在的分裂位点进行位点特异性失活。在正常的分裂周期中，MinD发挥两种作用。它激活负责使潜在分裂位点失活的MinC依赖性机制，并且它还使分裂抑制系统对拓扑特异性因子MinE敏感。MinE抑制细胞中部正常分裂位点处的分裂阻滞，但不抑制所有细胞极处的分裂阻滞，从而确保正常的分裂模式。在本研究中，MinD蛋白被纯化至同质，并显示其能结合ATP且具有ATP酶活性。当通过定点诱变改变MinD的假定ATP结合结构域时，突变蛋白不再能够激活MinC依赖性分裂抑制系统。免疫电子显微镜显示MinD位于细胞膜内膜区域。这些结果表明MinD是一种膜ATP酶，并表明ATP酶活性在正常分裂过程中MinD蛋白的功能中起重要作用。
