KapB is a lipoprotein required for KinB signal transduction and activation of the phosphorelay to sporulation in Bacillus subtilis
KapB is a lipoprotein required for KinB signal transduction and activation of the phosphorelay to sporulation in Bacillus subtilis
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DOI：
10.1046/j.1365-2958.1997.6542024.x
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发表时间：
1997-12-01
影响因子：
3.6
通讯作者：
Hoch, JA
中科院分区：
文献类型：
--
作者：
Dartois, V;Djavakhishvili, T;Hoch, JA
KinB是两种主要的组氨酸激酶之一，其在磷酸化酶中提供磷酸输入以产生类似于P的SpoOA，P是控制孢子形成起始的关键转录因子。搜索的插入突变体的KinB依赖的孢子形成的激活的影响，导致识别的Igt基因座编码的脂蛋白甘油基转移酶所需的前脂蛋白的脂质修饰之前，他们的分裂和易位跨细胞质膜。同时，在KapB中检测到一个假定的脂蛋白信号肽切割位点，已知该位点是KinB介导的孢子形成所严格需要的，并且位于KinB下游的单个转录单位中。使用PhoA肽融合，我们已经表明，KapB信号肽可以直接活性碱性磷酸酶的细胞质膜的外表面在一个LGT依赖性的方式，强烈表明KapB是一个脂蛋白拴系到外面的细胞质膜通过脂质锚。由于KapB被证明是kinBkapB操纵子表达的载体，构建了由融合到KinB激酶结构域的KinA传感器结构域（KinA“-”B）组成的嵌合激酶，以评估（i）KapB参与激酶反应的催化，和（ii）KinB体外磷酸化SpoOF的能力。结果表明，KapB在体内和体外均被KinA“-”B嵌合体激活磷酸化中继，并且KinA“-”B在体外直接磷酸化SpoOF。讨论了KapB在调节KinB活性中的作用的模型。
KinB is one of the two major histidine kinases that provide phosphate input in the phosphorelay to produce SpoOA similar to P, the key transcription factor controlling the initiation of sporulation. A search for insertion mutants affected in activation of KinB-dependent sporulation led to the identification of the Igt locus encoding the lipoprotein glyceryltransferase required for the lipid modification of prolipoproteins before their cleavage and translocation across the cytoplasmic membrane. In parallel, a putative lipoprotein signal peptide cleavage site was detected in KapB, known to be strictly required for KinB-mediated sporulation and located downstream of KinB in a single transcription unit. Using PhoA peptide fusions, we have shown that KapB signal-peptide can direct active alkaline phosphatase to the outer surface of the cytoplasmic membrane in an LGT-dependent manner, strongly suggesting that KapB is a lipoprotein tethered to the outer face of the cytoplasmic membrane via a lipid anchor. As KapB proved to be dispensable for expression of the kinBkapB operon, a chimeric kinase was built consisting of KinA sensor domain fused to KinB kinase domain (KinA'-'B) to assess (i) the involvement of KapB in catalysis of the kinase reaction, and (ii) the ability of KinB to phosphorylate SpoOF in vitro. It was shown that KapB is dispensable for both in vivo and in vitro activation of the phosphorelay by the KinA'-'B chimera and that KinA'-'B phosphorylates SpoOF directly in vitro, Models for the role of KapB in regulating KinB activity are discussed.