In vivo analysis of the roles of conserved aspartate and histidine residues within a complex response regulator
In vivo analysis of the roles of conserved aspartate and histidine residues within a complex response regulator
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DOI：
10.1111/j.1365-2958.2005.04491.x
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发表时间：
2005-03-01
影响因子：
3.6
通讯作者：
Kehoe, DM
中科院分区：
文献类型：
--
作者：
Li, L;Kehoe, DM
RcaC是一组具有复杂结构域组合的大型反应调节器的创始成员，其中至少包含两个接收域、OmpR类有翼螺旋-转角螺旋DNA结合域和组氨酸磷酸转移(HPT)结构域。在其两个受体和HPT结构域中，RcaC在天冬氨酸51、576和组氨酸316处含有共同的磷酸化位点。RcaC在调节光合作用捕光天线组件的基因转录以适应光色变化的途径中起作用。我们发现藻蓝蛋白基因的表达需要RcaC。RcaC参与藻红蛋白基因的光调节，但不是控制这些基因的第二光调节途径的一部分。天冬氨酸51或组氨酸316处的替换严重削弱了光响应，而天冬氨酸576处的替换几乎没有影响。光调节的完全丧失，通过藻蓝蛋白基因的表达来衡量，只在三个突变体中发生。我们得出结论，天冬氨酸51主要控制光色反应，并受组氨酸316调节，这些残基可能在红光下被磷酸化，在绿光下去磷酸化。羧基末端的接收器结构域在控制这种反应中起着次要的作用。RcaC的丰度也受光调控，依赖于天冬氨酸51和组氨酸316，而不是天冬氨酸576。
RcaC is the founding member of a group of large response regulators with complex domain combinations containing at least two receiver domains, an OmpR-class winged helix-turn-helix DNA binding domain, and a histidine phosphotransfer (HPt) domain. Within its two receiver and HPt domains, RcaC contains consensus phosphorylation sites at aspartates 51, 576 and histidine 316. RcaC operates in the pathway regulating transcription of genes encoding components of photosynthetic light harvesting antenna to changes in light colour. We show that phycocyanin gene expression requires RcaC. RcaC contributes to light regulation of phycoerythrin genes, but is not part of the second light regulation pathway controlling these genes. Substitutions at aspartate 51 or histidine 316 severely impaired light responsiveness while substitutions at aspartate 576 had little effect. Complete loss of light regulation, measured by phycocyanin gene expression, only occurred in the triple mutant. We conclude that aspartate 51 primarily controls light colour responsiveness and is regulated by histidine 316, and that these residues are likely phosphorylated in red light and dephosphorylated in green light. The carboxy-terminal receiver domain has a minor role in controlling this response. RcaC abundance is also light regulated and depends on aspartate 51 and histidine 316, but not aspartate 576.