Novel Photosensory Two-Component System (PixA-NixB-NixC) Involved in the Regulation of Positive and Negative Phototaxis of Cyanobacterium Synechocystis sp PCC 6803
Novel Photosensory Two-Component System (PixA-NixB-NixC) Involved in the Regulation of Positive and Negative Phototaxis of Cyanobacterium Synechocystis sp PCC 6803
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DOI：
10.1093/pcp/pcr155
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发表时间：
2011-12-01
影响因子：
4.9
通讯作者：
Ikeuchi, Masahiko
中科院分区：
文献类型：
--
作者：
Narikawa, Rei;Suzuki, Fumiko;Ikeuchi, Masahiko
集胞藻PCC 6803的两个野生型亚株对光源表现出正趋光性（PCC-P），对远离光源表现出负趋光性（PCC-N）。在这项研究中，我们发现一种新型的光响应双组分系统参与了趋光调节。失活slr 1212（pixA），它编码一个光感受器组氨酸激酶，恢复PCC-P的正趋光性为负趋光性，和失活的下游slr 1213（nixB）和slr 1214（nixC），分别编码AraC样转录因子型和PatA型反应调节，恢复PCC-N的负趋光性为正趋光性。pixA和nixBC破坏的相反作用意味着在正和负趋光性的切换中的意想不到的信号转导途径。蓝/绿型蓝藻色素GAF结构域的PixA在集胞藻和藻蓝胆素生产大肠杆菌中表达。该全蛋白共价结合发色团藻紫胆素，并显示出在紫色吸收（Pv，λ（峰值）= 396 nm）和绿色吸收（Pg，λ（峰值）= 533 nm）形式之间的可逆光转换，尽管来自E.大肠杆菌部分结合前体藻蓝胆素。这些结果进行了讨论的想法，PixA作为一个紫光受体的开关的积极和消极的趋光性的转录和功能调节。
Two wild-type substrains of a motile cyanobacterium Synechocystis sp. PCC 6803 show positive phototaxis toward a light source (PCC-P) and negative phototaxis away from light (PCC-N). In this study, we found that a novel two-component system of photoresponse is involved in the phototactic regulation. Inactivation of slr1212 (pixA), which encodes a photoreceptor histidine kinase, reverted the positive phototaxis of PCC-P to negative phototaxis, and inactivation of the downstream slr1213 (nixB) and slr1214 (nixC), which encode AraC-like transcription factor-type and PatA-type response regulators, respectively, reverted the negative phototaxis of PCC-N to positive phototaxis. Opposite effects of pixA and nixBC disruption implies an unexpected signal transduction pathway in the switching of positive and negative phototaxis. The blue/green-type cyanobacteriochrome GAF domain of PixA was expressed in Synechocystis and phycocyanobilin-producing Escherichia coli. The holoprotein covalently bound a chromophore phycoviolobilin and showed reversible photoconversion between the violet- (Pv, lambda(peak) = 396 nm) and green-absorbing (Pg, lambda(peak) = 533 nm) forms, although the protein from E. coli partially bound a precursor phycocyanobilin. These results were discussed with regard to an idea that PixA serves as a violet light receptor for switching of positive and negative phototaxis by transcriptional and functional regulation.