Sharp Marc D, Pogliano Kit
Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA.
EMBO J. 2002 Nov 15;21(22):6267-74. doi: 10.1093/emboj/cdf597.
During Bacillus subtilis sporulation, the SpoIIIE DNA translocase moves a trapped chromosome across the sporulation septum into the forespore. The direction of DNA translocation is controlled by the specific assembly of SpoIIIE in the mother cell and subsequent export of DNA into the forespore. We present evidence that the MinCD heterodimer, which spatially regulates cell division during vegetative growth, serves as a forespore-specific inhibitor of SpoIIIE assembly. The deletion of minCD increases the ability of forespore-expressed SpoIIIE to assemble and translocate DNA, and causes otherwise wild-type cells to reverse the direction of DNA transfer, producing anucleate forespores. We propose that two distinct mechanisms ensure the specific assembly of SpoIIIE in the mother cell, the partitioning of more SpoIIIE molecules into the larger mother cell by asymmetric cell division and the MinCD-dependent repression of SpoIIIE assembly in the forespore. Our results suggest that the ability of MinCD to sense positional information is utilized during sporulation to regulate protein assembly differentially on the two faces of the sporulation septum.
在枯草芽孢杆菌形成芽孢的过程中，SpoIIIE DNA转位酶将一条被困的染色体穿过芽孢形成隔膜转运至前芽孢中。DNA转位的方向由SpoIIIE在母细胞中的特异性组装以及随后将DNA输出到前芽孢中控制。我们提供的证据表明，在营养生长期间对细胞分裂进行空间调控的MinCD异源二聚体，作为前芽孢特异性的SpoIIIE组装抑制剂。minCD的缺失增强了在前芽孢中表达的SpoIIIE组装和转运DNA的能力，并导致原本野生型的细胞逆转DNA转移方向，产生无核前芽孢。我们提出，两种不同的机制确保了SpoIIIE在母细胞中的特异性组装，即通过不对称细胞分裂将更多的SpoIIIE分子分配到更大的母细胞中，以及MinCD对前芽孢中SpoIIIE组装的依赖性抑制。我们的结果表明，MinCD感知位置信息的能力在芽孢形成过程中被用于在芽孢形成隔膜的两个面上差异性地调节蛋白质组装。
