Sciochetti Stephen A, Ohta Noriko, Newton Austin
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Mol Microbiol. 2005 Jun;56(6):1467-80. doi: 10.1111/j.1365-2958.2005.04652.x.
DivL is an essential tyrosine kinase in Caulobacter crescentus that controls an early step in the cell division cycle. We show here that DivL dynamically localizes to the stalk-distal cell pole and less frequently to the stalked cell pole during the S-phase. The kinase is subsequently released from the cell poles late in division and remains dispersed in the newly divided progeny stalk and swarmer cells. Mutational analysis of DivL in a DivL-GFP fusion protein demonstrated that the extreme C-terminus and residues in the conserved four-helix bundle, which is the phosphorylation-dimerization domain, are important for localization. We speculate that the four-helix bundle of the core catalytic domain may serve as a recognition site for the "localization machinery". Unexpectedly, a DivL protein with mutations in the C-terminal localization sequence, and an intact catalytic domain, efficiently complemented a divL null mutation. Thus, subcellular localization of DivL is not essential to its function in cell division regulation. Regulation of cell division by DivL does, however, depend on its localization in the cell membrane.
DivL是新月柄杆菌中一种重要的酪氨酸激酶，它控制细胞分裂周期的早期步骤。我们在此表明，DivL在S期动态定位于柄远端细胞极，较少定位于有柄细胞极。该激酶随后在分裂后期从细胞极释放，并在新分裂的子代柄细胞和游动细胞中保持分散状态。对DivL-GFP融合蛋白中的DivL进行突变分析表明，极端C末端和保守的四螺旋束中的残基（即磷酸化二聚化结构域）对定位很重要。我们推测，核心催化结构域的四螺旋束可能作为“定位机制”的识别位点。出乎意料的是，在C末端定位序列中具有突变且催化结构域完整的DivL蛋白有效地补充了divL缺失突变。因此，DivL的亚细胞定位对其在细胞分裂调控中的功能并非必不可少。然而，DivL对细胞分裂的调控确实取决于其在细胞膜中的定位。
