Vats Purva, Shih Yu-Ling, Rothfield Lawrence
Department of Molecular, Microbial and Structural Biology, University of Connecticut, Health Center, Farmington, CT 06030, USA.
Mol Microbiol. 2009 Apr;72(1):170-82. doi: 10.1111/j.1365-2958.2009.06632.x. Epub 2009 Feb 11.
The Escherichia coli actin homologue MreB is part of a helical cytoskeletal structure that winds around the cell between the two poles. It has been shown that MreB redistributes during the cell cycle to form circumferential ring structures that flank the cytokinetic FtsZ ring and appear to be associated with division and segregation of the helical cytoskeleton. We show here that the MreB cytoskeletal ring also contains the MreC, MreD, Pbp2 and RodA proteins. Assembly of MreB, MreC, MreD and Pbp2 into the ring structure required the FtsZ ring but no other known components of the cell division machinery, whereas assembly of RodA into the cytoskeletal ring required one or more additional septasomal components. Strikingly, MreB, MreC, MreD and RodA were each able to independently assemble into the cytoskeletal ring and coiled cytoskeletal structures in the absence of any of the other ring components. This excludes the possibility that one or more of these proteins acts as a scaffold for incorporation of the other proteins into these structures. In contrast, incorporation of Pbp2 required the presence of MreC, which may provide a docking site for Pbp2 entry.
大肠杆菌肌动蛋白同源物MreB是一种螺旋状细胞骨架结构的一部分，该结构在细胞两极之间环绕细胞。研究表明，MreB在细胞周期中重新分布，形成环绕细胞分裂FtsZ环的周向环状结构，并且似乎与螺旋状细胞骨架的分裂和分离有关。我们在此表明，MreB细胞骨架环还包含MreC、MreD、Pbp2和RodA蛋白。MreB、MreC、MreD和Pbp2组装成环状结构需要FtsZ环，但不需要细胞分裂机制的其他已知成分，而RodA组装到细胞骨架环中则需要一种或多种额外的隔膜体成分。引人注目的是，在没有任何其他环成分的情况下，MreB、MreC、MreD和RodA各自都能够独立组装成细胞骨架环和螺旋状细胞骨架结构。这排除了这些蛋白质中的一种或多种作为将其他蛋白质纳入这些结构的支架的可能性。相比之下，Pbp2的掺入需要MreC的存在，MreC可能为Pbp2进入提供一个对接位点。
