Szeto Tim H, Rowland Susan L, Rothfield Lawrence I, King Glenn F
Department of Biochemistry, University of Connecticut Health Center, 263 Farmington Avenue, 06032, USA.
Proc Natl Acad Sci U S A. 2002 Nov 26;99(24):15693-8. doi: 10.1073/pnas.232590599. Epub 2002 Nov 7.
MinD is a widely conserved ATPase that has been demonstrated to play a pivotal role in selection of the division site in eubacteria and chloroplasts. It is a member of the large ParA superfamily of ATPases that are characterized by a deviant Walker-type ATP-binding motif. MinD localizes to the cytoplasmic face of the inner membrane in Escherichia coli, and its association with the inner membrane is a prerequisite for membrane recruitment of the septation inhibitor MinC. However, the mechanism by which MinD associates with the membrane has proved enigmatic; it seems to lack a transmembrane domain and the amino acid sequence is devoid of hydrophobic tracts that might predispose the protein to interaction with lipids. In this study, we show that the extreme C-terminal region of MinD contains a highly conserved 8- to 12-residue sequence motif that is essential for membrane localization of the protein. We provide evidence that this motif forms an amphipathic helix that most likely mediates a direct interaction between MinD and membrane phospholipids. A model is proposed whereby the membrane-targeting motif mediates the rapid cycles of membrane attachment-release-reattachment that are presumed to occur during pole-to-pole oscillation of MinD in E. coli.
MinD是一种广泛保守的ATP酶，已被证明在真细菌和叶绿体的分裂位点选择中起关键作用。它是ATP酶的大型ParA超家族的成员，其特征是具有异常的沃克型ATP结合基序。MinD定位于大肠杆菌内膜的细胞质面，它与内膜的结合是隔膜抑制剂MinC膜募集的先决条件。然而，MinD与膜结合的机制一直是个谜；它似乎缺乏跨膜结构域，并且氨基酸序列中没有可能使蛋白质易于与脂质相互作用的疏水区域。在这项研究中，我们表明MinD的极端C末端区域包含一个高度保守的8至12个残基的序列基序，该基序对于蛋白质的膜定位至关重要。我们提供的证据表明，该基序形成了一个两亲性螺旋，最有可能介导MinD与膜磷脂之间的直接相互作用。提出了一个模型，据此膜靶向基序介导了在大肠杆菌中MinD极到极振荡期间假定发生的膜附着-释放-重新附着的快速循环。
