Roles for MreC and MreD proteins in helical growth of the cylindrical cell wall in Bacillus subtilis
Roles for MreC and MreD proteins in helical growth of the cylindrical cell wall in Bacillus subtilis
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DOI：
10.1111/j.1365-2958.2005.04736.x
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发表时间：
2005-09-01
影响因子：
3.6
通讯作者：
Errington, J
中科院分区：
文献类型：
--
作者：
Leaver, M;Errington, J
MreB家族的肌动蛋白同源物在确定许多非球形真细菌的形态方面具有重要作用。mreC和mreD基因与细胞形态的控制有关，但其确切功能尚不清楚。在枯草芽孢杆菌中，MreB同源物Mbl指导新的细胞壁材料螺旋插入杆状细胞的圆柱形部分。MreC或MreD的耗尽取消了对细胞形状的控制。在存在高浓度镁的情况下，耗尽MreC或MreD的细胞可以无限繁殖，尽管它们具有球形形状。我们发现，球状突变体的生长是基于在细胞分裂位点插入新的壁材料，这种局部化的生长依赖于细胞分裂。在某些条件下，MreC和MreD蛋白定位于螺旋构型。这种定位模式类似于Mbl蛋白的螺旋电缆。这些结果表明，MreC和MreD在形态发生途径中起作用，所述形态发生途径将螺旋状胞质Mbl缆线偶联到细胞外细胞壁合成机构，这对于杆状细胞的圆柱形伸长是至关重要的。
Actin homologues of the MreB family have an important role in specifying the morphology of many non-spherical eubacteria. The mreC and mreD genes have been implicated in control of cell morphology but their precise functions are unknown. In Bacillus subtilis the MreB homologue Mbl directs helical insertion of new cell wall material in the cylindrical part of the rod-shaped cell. Depletion of either MreC or MreD abolishes the control of cell shape. In the presence of high concentrations of magnesium cells depleted of MreC or MreD can be propagated indefinitely, although they have a spheroidal shape. We show that growth of the spheroidal mutants is based on insertion of new wall material at cell division sites and that this localized growth is dependent on cell division. Under some conditions the MreC and MreD proteins localize in a helical configuration. This localization pattern resembles that of the helical cables of Mbl protein. These results suggest that MreC and MreD act in a morphogenic pathway that couples the helical cytosolic Mbl cables to the extracellular cell wall synthetic machinery, which is critical for cylindrical elongation of the rod-shaped cells.