Citrate sensing by the C4-dicarboxylate/citrate sensor kinase DcuS of Escherichia coli:: Binding site and conversion of DcuS to a C4-dicarboxylate- or citrate-specific sensor
Citrate sensing by the C4-dicarboxylate/citrate sensor kinase DcuS of Escherichia coli:: Binding site and conversion of DcuS to a C4-dicarboxylate- or citrate-specific sensor
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DOI：
10.1128/jb.00168-07
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发表时间：
2007-06-01
影响因子：
3.2
通讯作者：
Unden, G.
中科院分区：
文献类型：
--
作者：
Kraemer, J.;Fischer, J. D.;Unden, G.
大肠杆菌的组氨酸蛋白激酶DcuS通过胞外结构域感应C、-二羧酸和柠檬酸。密切相关的传感器激酶CRA通过一个同源的外质结构域结合柠檬酸盐，但不结合C -二羧酸盐。已知CitA通过C1， C2， C3和h位点结合柠檬酸盐的三个羧酸盐和羟基，DcuS需要相同的位点来感应c -4-二羧酸盐，但只有C2和C3是高度保守的。这里显示，dcu对柠檬酸盐的感应需要相同的位点。因此，柠檬酸盐与dcu的结合与c -4-二羧酸盐的结合相似，但与CitA中柠檬酸盐的结合不同。dcu可以通过突变C1和C3位点残基或某些dcu亚型特异性残基转化为c -4-二羧酸特异性传感器（dcu (DC)）。C1位点周围的突变旨在增加该位点的大小和可及性，将dcu转化为柠檬酸盐特异性传感器（dcu (Cit)）。DcuS（DC）和DcuS（Cit）具有互补的效应特异性，对c -4-二羧酸盐或柠檬酸盐和mesaconate均有反应。结果表明，dcu通过分子的c -4-二羧酸盐部分与柠檬酸盐（类似于c -4-二羧酸盐）结合。C2和C3位点是柠檬酸盐或c -4-二羧酸盐的两个羧基结合所必需的；场地C1和H用于其他基本用途。
The histidine protein kinase DcuS of Escherichia coli senses C,-dicarboxylates and citrate by a periplasmic domain. The closely related sensor kinase CRA binds citrate, but no C,-dicarboxylates, by a homologous periplasmic domain. CitA is known to bind the three carboxylate and the hydroxyl groups of citrate by sites C1, C2, C3, and H. DcuS requires the same sites for C-4-dicarboxylate sensing, but only C2 and C3 are highly conserved. It is shown here that sensing of citrate by DcuS required the same sites. Binding of citrate to DcuS, therefore, was similar to binding of C-4-dicarboxylates but different from that of citrate binding in CitA. DcuS could be converted to a C-4-dicarboxylate-specific sensor (DcuS(DC)) by mutating residues of sites C1 and C3 or of some DcuS-subtype specific residues. Mutations around site C1 aimed at increasing the size and accessibility of the site converted DcuS to a citrate-specific sensor (DcuS(Cit)). DcuS(DC) and DcuS(Cit) had complementary effector specificities and responded either to C-4-dicarboxylates or to citrate and mesaconate. The results imply that DcuS binds citrate (similar to the C-4-dicarboxylates) via the C-4-dicarboxylate part of the molecule. Sites C2 and C3 are essential for binding of two carboxylic groups of citrate or of C-4-dicarboxylates; sites C1 and H are required for other essential purposes.