Membrane sequestration of the signal transduction protein GlnK by the ammonium transporter AmtB
Membrane sequestration of the signal transduction protein GlnK by the ammonium transporter AmtB
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DOI：
10.1093/emboj/21.4.536
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发表时间：
2002-02-15
期刊：
影响因子：
11.4
通讯作者：
Merrick, M
中科院分区：
文献类型：
--
作者：
Coutts, G;Thomas, G;Merrick, M
铵转运蛋白是铵转运蛋白，在生命的所有领域都是保守的，存在于细菌、古细菌和真核生物中。在细菌和古生菌中，细菌结构基因（amtB）总是与glnK连接，glnK编码P-II信号转导蛋白家族的成员，该蛋白调节酶活性和基因表达以响应细胞内氮状态。我们现在已经表明，在大肠杆菌和棕色固氮菌中，GlnK以AmtB依赖的方式结合到膜上，并且GlnK充当AmtB转运活性的负调节剂。膜结合依赖于GlnK的尿苷酰化状态，并根据细胞氮状态进行调节，使得其在氮充足的情况下最大。AmtB对GlnK的膜隔离代表了一种新的信号转导形式，其中整合的膜转运蛋白的功能是将细胞外铵浓度与细胞内对氮状态的反应联系起来。这些结果也为P-II蛋白的进化提供了新的见解，并为它们的三角对称性提供了理论基础。
The Amt proteins are ammonium transporters that are conserved throughout all domains of life, being found in bacteria, archaea and eukarya. In bacteria and archaea, the Amt structural genes (amtB) are invariably linked to glnK, which encodes a member of the P-II signal transduction protein family, proteins that regulate enzyme activity and gene expression in response to the intracellular nitrogen status. We have now shown that in Escherichia coli and Azotobacter vinelandii, GlnK binds to the membrane in an AmtB-dependent manner and that GlnK acts as a negative regulator of the transport activity of AmtB. Membrane binding is dependent on the uridylylation state of GlnK and is modulated according to the cellular nitrogen status such that it is maximal in nitrogen-sufficient situations. The membrane sequestration of GlnK by AmtB represents a novel form of signal transduction in which an integral membrane transport protein functions to link the extracellular ammonium concentration to the intracellular responses to nitrogen status. The results also offer new insights into the evolution of P-II proteins and a rationale for their trigonal symmetry.