Role of the stress sigma factor RpoS in GacA/RsmA-controlled secondary metabolism and resistance to oxidative stress in Pseudomonas fluorescens CHA0
Role of the stress sigma factor RpoS in GacA/RsmA-controlled secondary metabolism and resistance to oxidative stress in Pseudomonas fluorescens CHA0
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DOI：
10.1016/j.femsle.2004.12.008
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发表时间：
2005-02-01
影响因子：
2.1
通讯作者：
Haas, D
中科院分区：
文献类型：
--
作者：
Heeb, S;Valverde, C;Haas, D
在荧光假单胞菌生物控制菌株CHA 0中，双组分系统GacS/GacA通过上调小调节RNA的转录来积极控制细胞外产物如氰化氢、蛋白酶和2，4-二乙酰基间苯三酚的合成，所述小调节RNA减轻RsmA介导的靶基因的翻译抑制。应激σ因子（sigma（S）（RpoS）的表达受GacA的正调控，受RsmA的负调控。与野生型CHA 0相比，gacS和rpoS无效突变体在稳定期对H2 O2更敏感。rpoS或rsmZ的过表达，编码对抗RsmA的小RNA。恢复了gacS突变体的过氧化物抗性。相比之下，rpoS突变体显示hcnA（HCN合酶亚基）基因和aprA（主要外切蛋白酶）基因的表达略有增加，而我们的过度表达强烈降低了这些基因的表达。这些结果表明，在菌株CHA 0，外产物合成的调节不涉及我们作为中间体的Gac/Rsm信号转导途径，而我们参与Gac/Rsm介导的抗氧化应激。(C)2004年，欧洲微生物学会联合会。Elsevier B. V.出版，保留所有权利。
In Pseudomonasfluorescens biocontrol strain CHA0, the two-component system GacS/GacA positively controls the synthesis of extracellular products such as hydrogen cyanide, protease, and 2,4-diacetylphloroglucinol, by upregulating the transcription of small regulatory RNAs which relieve RsmA-mediated translational repression of target genes. The expression of the stress sigma factor (sigma(S) (RpoS) was controlled positively by GacA and negatively by RsmA. By comparison with the wild-type CHA0, both a gacS and an rpoS null mutant were more sensitive to H2O2 in stationary phase. Overexpression of rpoS or of rsmZ, encoding a small RNA antagonistic to RsmA. restored peroxide resistance to a gacS mutant. By contrast, the rpoS mutant showed a slight increase in the expression of the hcnA (HCN synthase subunit) gene and of the aprA (major exoprotease) gene, whereas overexpression of us strongly reduced the expression of these genes. These results suggest that in strain CHA0, regulation of exoproduct synthesis does not involve us as an intermediate in the Gac/Rsm signal transduction pathway whereas us participates in Gac/Rsm-mediated resistance to oxidative stress. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.