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PrhN, a putative marR family transcriptional regulator, is involved in positive regulation of type III secretion system and full virulence of Ralstonia solanacearum.

ABSTRACT: The MarR-family of transcriptional regulators are involved in various cellular processes, including resistance to multiple antibiotics and other toxic chemicals, adaptation to different environments and pathogenesis in many plant and animal pathogens. Here, we reported a new MarR regulator PrhN, which was involved in the pathogenesis of Ralstonia solanacearum. prhN mutant exhibited significantly reduced virulence and stem colonization compared to that of wild type in tomato plants. prhN mutant caused identical hypersensitive response (HR) on resistant plants to the wild type. Deletion of prhN gene substantially reduced the expression of type III secretion system (T3SS) in vitro and in planta (mainly in tomato plants), which is essential for pathogenicity of R. solanacearum, and the complemented PrhN could restore its virulence and T3SS expression to that of wild type. T3SS is directly controlled by AraC-type transcriptional regulator HrpB, and the transcription of hrpB is activated by HrpG and PrhG. HrpG and PrhG are homologs but are regulated by the PhcA positively and negatively, respectively. Deletion of prhN gene also abolished the expression of hrpB and prhG, but didn't change the expression of hrpG and phcA. Together, these results indicated that PrhN positively regulates T3SS expression through PrhG and HrpB. PrhN and PhcA should regulate prhG expression in a parallel way. This is the first report on the pathogenesis of MarR regulator in R. solanacearum, and this new finding will improve our understanding on the various biological functions of MarR regulator and the complex regulatory network on hrp regulon in R. solanacearum.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC4412082 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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PrhN, a putative marR family transcriptional regulator, is involved in positive regulation of type III secretion system and full virulence of Ralstonia solanacearum.

Zhang Yong Y Luo Feng F Wu Dousheng D Hikichi Yasufumi Y Kiba Akinori A Igarashi Yasuo Y Ding Wei W Ohnishi Kouhei K

Frontiers in microbiology 20150428

The MarR-family of transcriptional regulators are involved in various cellular processes, including resistance to multiple antibiotics and other toxic chemicals, adaptation to different environments and pathogenesis in many plant and animal pathogens. Here, we reported a new MarR regulator PrhN, which was involved in the pathogenesis of Ralstonia solanacearum. prhN mutant exhibited significantly reduced virulence and stem colonization compared to that of wild type in tomato plants. prhN mutant c ...[more]

PMID: 25972849

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Project description:Ralstonia solanacearum species complex (RSSC) posses extremely abundant type III effectors (T3Es) that are translocated into plant cells via a syringe-like apparatus assembled by a type III secretion system (T3SS) to subvert host defense initiated by innate immunity. More than 100 T3Es are predicted among different RSSC strains, with an average of about 70 T3Es in each strain. Among them, 32 T3Es are found to be conserved among the RSSC and hence called the core T3Es. Here, we genetically characterized contribution of abundant T3Es to virulence of a Japanese RSSC strain OE1-1 toward host plants. While all the T3Es members of AWR family contributed slightly to virulence, those of the GALA, HLK, and SKWP families did not influence full virulence of OE1-1. Mutant OE1-1D21E (with deletion of all 21 T3Es members of four families) exhibited slightly impaired virulence, while mutant OE1-1D36E (deleting all 21 T3Es of 4 families and 15 core T3Es) exhibited substantially reduced virulence. Mutant OE1-1D42E (deleting all 21 T3Es of 4 families, 15 core T3Es and 6 extended core T3Es) failed to cause any disease on tobacco plants with leaf infiltration but retained faint virulence on tobacco plants with petiole inoculation. The proliferation of mutant OE1-1D42E in tobacco stems was substantially impaired with about three orders of magnitude less than that of OE1-1, while no impact in tobacco leaves if directly infiltrated into leaves. On the contrary, the OE1-1D42E mutant retained faint virulence on eggplants with leaf infiltration but completely lost virulence on eggplants with root-cutting inoculation. The proliferation of OE1-1D42E mutant both in eggplant leaves and stems was substantially impaired. Intriguingly, mutant OE1-1D42E still caused necrotic lesions in tobacco and eggplant leaves, indicating that some other than the 42 removed effectors are involved in expansion of necrotic lesions in host leaves. All taken together, we here genetically demonstrated that all the core and extended core T3Es are nearly crucial for virulence of OE1-1 toward host plants and provided currently a kind of T3Es-free strain that enables primary functional studies of individual T3Es in host cells.

Dataset Information

PrhN, a putative marR family transcriptional regulator, is involved in positive regulation of type III secretion system and full virulence of Ralstonia solanacearum.

Publications

PrhN, a putative marR family transcriptional regulator, is involved in positive regulation of type III secretion system and full virulence of Ralstonia solanacearum.

Similar Datasets

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