Identification and characterization of chemosensors for d-malate, unnatural enantiomer of malate, in Ralstonia pseudosolanacearum.
Identification and characterization of chemosensors for d-malate, unnatural enantiomer of malate, in Ralstonia pseudosolanacearum.
复制标题
假茄青菌中 d-苹果酸（苹果酸的非天然对映体）化学传感器的鉴定和表征。
DOI：
10.1099/mic.0.000408
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发表时间：
2017
期刊：
影响因子：
1.5
通讯作者：
Junichi Kato
中科院分区：
文献类型：
--
作者：
Mattana Tunchai;Akiko Hida;Shota Oku;Yutaka Nakashimada;Takahisa Tajima;Junichi Kato
假solanacearumps29被非代谢苹果酸吸引，这是一种非天然的对映体。对Ps29单mcp基因缺失突变体的完整筛选显示，RSc1156同源物是一种苹果酸盐的化学传感器。Ps29的RSc1156同源缺失突变体对苹果酸盐的反应减少但显著，表明存在另一种苹果酸盐化学传感器。McpM先前已被确定为一种对苹果酸盐的化学传感器。我们构建了一个RSc1156同源的emcpm双缺失突变体，并注意到该突变体对苹果酸盐没有反应；因此，RSc1156同源物和McpM是该生物体内苹果酸盐的主要化学传感器。为了进一步表征RSc1156同系物和McpM的配体特异性，我们构建了Ps29衍生物（命名为K18），其中包含18个单个mcp基因的缺失，包括mcpm和RSc1156。含有RSc1156同源基因的K18对苹果酸盐和苹果酸盐反应强烈，对苹果酸盐反应中等，但对苹果酸盐和琥珀酸盐反应不强烈。含有mcm的K18对苹果酸盐和酒石酸盐反应强烈，对琥珀酸盐、富马酸盐和苹果酸盐反应温和。Ps29利用苹果酸盐和酒石酸盐，但不利用苹果酸盐。因此，我们得出结论，l-酒石酸盐和l-苹果酸盐分别是RSc1156同源物和McpM的天然配体，而对苹果酸盐的趋化性是RSc1156同源物和McpM在Ps29中的偶然反应。我们建议将RSc1156同源物重新命名为McpT。在番茄植株侵染试验中，高毒力r。pseudosolanacearumMAFF106611的侵染能力与野生型MAFF106611相当，表明mcpt介导的趋化作用在番茄植株侵染中并不起重要作用。
Ralstonia pseudosolanacearumPs29 is attracted by nonmetabolizabled-malate, an unnatural enantiomer. Screening of a complete collection of single-mcp-gene deletion mutants of Ps29 revealed that the RSc1156 homologue is a chemosensor ford-malate. An RSc1156 homologue deletion mutant of Ps29 showed decreased but significant responses tod-malate, suggesting the existence of anotherd-malate chemosensor. McpM previously had been identified as a chemosensor forl-malate. We constructed an RSc1156 homologuemcpMdouble deletion mutant and noted that this mutant failed to respond tod-malate; thus, the RSc1156 homologue and McpM are the major chemosensors ford-malate in this organism. To further characterize the ligand specificities of the RSc1156 homologue and McpM, we constructed a Ps29 derivative (designated K18) harbouring deletions in 18 individualmcpgenes, includingmcpMand RSc1156. K18 harbouring the RSc1156 homologue responded strongly tol-tartrate andd-malate and moderately tod-tartrate, but not tol-malate or succinate. K18 harbouringmcpMresponded strongly tol-malate andd-tartrate and moderately to succinate, fumarate andd-malate. Ps29 utilizesl-malate andl-tartrate, but notd-malate. We therefore concluded thatl-tartrate andl-malate are natural ligands of the RSc1156 homologue and McpM, respectively, and that chemotaxis towardd-malate is a fortuitous response by the RSc1156 homologue and McpM in Ps29. We propose re-designation of the RSc1156 homologue as McpT. In tomato plant infection assays, themcpTdeletion mutant of highly virulentR. pseudosolanacearumMAFF106611 was as infectious as wild-type MAFF106611, suggesting that McpT-mediated chemotaxis does not play an important role in tomato plant infection.