CheY-dependent methylation of the asparagine receptor, McpB, during chemotaxis in Bacillus subtilis
CheY-dependent methylation of the asparagine receptor, McpB, during chemotaxis in Bacillus subtilis
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DOI：
10.1074/jbc.274.16.11092
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发表时间：
1999-04-16
影响因子：
4.8
通讯作者：
Ordal, GW
中科院分区：
文献类型：
--
作者：
Kirby, JR;Saulmon, MM;Ordal, GW
对于革兰氏阳性菌枯草芽孢杆菌，对引诱剂天冬酰胺的趋化作用是由化学受体McpB介导的。在这项研究中，我们证明了枯草杆菌McpB的快速净去甲基化导致了甲醇的即时产生，这可能是由于CheB的作用。我们还表明，天冬酰胺的添加和去除都会导致McpB的净去甲基化。每次去甲基化后，McpB被重新甲基化到接近刺激前的水平。这两个再甲基化事件都归因于使用S-腺苷蛋氨酸作为底物的Cher。因此，在枯草杆菌的趋化性过程中，不需要假设发生甲基转移到中间载体，正如先前所建议的那样。此外，我们发现天冬酰胺结合的McpB的再甲基化需要反应调节因子Chey-P，这表明Chey-P在枯草杆菌趋化过程中起反馈机制以促进对正刺激的适应。这一假说得到了两个观察的支持：cheRBCD突变体能够瞬时激发和随后的振荡，使鞭毛旋转偏向低于系留细胞试验中的刺激前的值，以及cheRBCD突变体能够聚集在胰蛋白音温板中。
For the Gram-positive organism Bacillus subtilis, chemotaxis to the attractant asparagine is mediated by the chemoreceptor McpB. In this study, we show that rapid net demethylation of B. subtilis McpB results in the immediate production of methanol, presumably due to the action of CheB. We also show that net demethylation of McpB occurs upon both addition and removal of asparagine. After each demethylation event, McpB is remethylated to nearly prestimulus levels. Both remethylation events are attributable to CheR using S-adenosylmethionine as a substrate. Therefore, no methyl transfer to an intermediate carrier need be postulated to occur during chemotaxis in B. subtilis as was previously suggested. Furthermore, we show that the remethylation of asparagine-bound McpB requires the response regulator, CheY-P, suggesting that CheY-P acts in a feedback mechanism to facilitate adaptation to positive stimuli during chemotaxis in B. subtilis, This hypothesis is supported by two observations: a cheRBCD mutant is capable of transient excitation and subsequent oscillations that bring the flagellar rotational bias below the prestimulus value in the tethered cell assay, and the cheRBCD mutant is capable of swarming in a Tryptone swarm plate.