scholarly journals Functional Characterization of RsRsgA for Ribosome Biosynthesis and Expression of the Type III Secretion System in Ralstonia solanacearum

2020 ◽  
Vol 33 (7) ◽  
pp. 972-981
Author(s):  
Jiaman Li ◽  
Liangliang Han ◽  
Nan Chen ◽  
Chao Zhu ◽  
Yuwei Gao ◽  
...  
Keyword(s):  
Ralstonia Solanacearum ◽  
Type Iii Secretion ◽  
Functional Characterization ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
In Planta ◽  
Tobacco Leaves ◽  
Type Iii ◽  
30S Subunit ◽  
Ribosome Biosynthesis

RsgA plays an important role in maturation of 30S subunit in many bacteria that assists in the release of RbfA from the 30S subunit during a late stage of ribosome biosynthesis. Here, we genetically characterized functional roles of RsgA in Ralstonia solanacearum, hereafter designated RsRsgA. Deletion of R. solanacearum rsgA or rbfA resulted in distinct deficiency of 16S ribosomal RNA, significantly slowed growth in broth medium, and diminished growth in nutrient-limited medium, which are similar as phenotypes of rsgA mutants and rbfA mutants of Escherichia coli and other bacteria. Our gene-expression studies revealed that RsRsgA is important for expression of genes encoding the type III secretion system (T3SS) (a pathogenicity determinant of R. solanacearum) both in vitro and in planta. Compared with the wild-type R. solanacearum strain, proliferation of the rsgA and rbfA mutants in tobacco leaves was significantly impaired, while they failed to migrate into tobacco xylem vessels from infiltrated leaves, and hence, these two mutants failed to cause any bacterial wilt disease in tobacco plants. It was further revealed that rsgA expression was highly enhanced under nutrient-limited conditions compared with that in broth medium and RsRsgA affects T3SS expression through the PrhN-PrhG-HrpB pathway. Moreover, expression of a subset of type III effectors was substantially impaired in the rsgA mutant, some of which are responsible for R. solanacearum GMI1000 elicitation of a hypersensitive response (HR) in tobacco leaves, while RsRsgA is not required for HR elicitation of GMI1000 in tobacco leaves. All these results provide novel insights into understanding various biological functions of RsgA proteins and complex regulation on the T3SS in R. solanacearum.

scholarly journals Components of the Pseudomonas syringae Type III Secretion System Can Suppress and May Elicit Plant Innate Immunity

2010 ◽  
Vol 23 (6) ◽  
pp. 727-739 ◽  
Author(s):  
Hye-Sook Oh ◽  
Duck Hwan Park ◽  
Alan Collmer
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Leaf Tissue ◽  
Secretion System ◽  
Colony Development ◽  
Plant Responses ◽  
In Planta ◽  
Callose Deposition ◽  
Type Iii

The type III secretion system (T3SS) of Pseudomonas syringae translocates into plant cells multiple effectors that suppress pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). P. syringae pv. tomato DC3000 no longer delivers the T3SS translocation reporter AvrPto-Cya in Nicotiana benthamiana leaf tissue in which PTI was induced by prior inoculation with P. fluorescens(pLN18). Cosmid pLN18 expresses the T3SS system of P. syringae pv. syringae 61 but lacks the hopA1Psy61 effector gene. P. fluorescens(pLN18) expressing HrpHPtoDC3000 or HopP1PtoDC3000, two T3SS-associated putative lytic transglycosylases, suppresses PTI, based on multiple assays involving DC3000 challenge inoculum (AvrPto-Cya translocation, hypersensitive response elicitation, and colony development in planta) or on plant responses (vascular dye uptake or callose deposition). Analysis of additional mutations in pHIR11 derivatives revealed that the pLN18-encoded T3SS elicits a higher level of reactive oxygen species (ROS) than does P. fluorescens without a T3SS, that enhanced ROS production is dependent on the HrpK1 translocator, and that HopA1Psy61 suppresses ROS elicitation attributable to both the P. fluorescens PAMPs and the presence of a functional T3SS.

scholarly journals Oleanolic Acid Induces the Type III Secretion System of Ralstonia solanacearum

2015 ◽  
Vol 6 ◽  
Author(s):  
Dousheng Wu ◽  
Wei Ding ◽  
Yong Zhang ◽  
Xuejiao Liu ◽  
Liang Yang
Keyword(s):  
Oleanolic Acid ◽  
Ralstonia Solanacearum ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii

scholarly journals Two Type III Secretion System Effectors from Ralstonia solanacearum GMI1000 Determine Host-Range Specificity on Tobacco

2009 ◽  
Vol 22 (5) ◽  
pp. 538-550 ◽  
Author(s):  
Marie Poueymiro ◽  
Sébastien Cunnac ◽  
Patrick Barberis ◽  
Laurent Deslandes ◽  
Nemo Peeters ◽  
...  
Keyword(s):  
Host Range ◽  
Ralstonia Solanacearum ◽  
Type Iii Secretion ◽  
Tandem Repeats ◽  
Hypervariable Region ◽  
Type Iii Secretion System ◽  
Defense Responses ◽  
Secretion System ◽  
Tobacco Plants ◽  
Type Iii

The model pathogen Ralstonia solanacearum GMI1000 is the causal agent of the bacterial wilt disease that attacks many solanaceous plants and other hosts but not tobacco (Nicotiana spp.). We found that two type III secretion system effector genes, avrA and popP1, are limiting the host range of strain GMI1000 on at least three tobacco species (N. tabacum, N. benthamiana, and N. glutinosa). Both effectors elicit the hypersensitive response (HR) on these tobacco species, although in different manners; AvrA is the major determinant recognized by N. tabacum and N. benthamiana, while PopP1 appears to be the major HR elicitor on N. glutinosa. Only the double inactivation of the avrA and popP1 genes allowed GMI1000 to wilt tobacco plants, thus showing that GMI1000 intrinsically possesses the functions necessary to wilt tobacco plants. A focused analysis on AvrA revealed that the first 58 N-terminal amino acids are sufficient to direct its injection into plant cells. We identified a hypervariable region in avrA, which contains variable numbers of tandem repeats (VNTR), each composed of 12 base pairs. We show that an 18–amino acid region in which the VNTR insertion occurs is an important domain involved in HR elicitation on N. benthamiana. avrA appears to be the target of various DNA insertions or mobile elements that probably allow R. solanacearum to evade the recognition and defense responses of tobacco.

scholarly journals Functional Characterization of SsaE, a Novel Chaperone Protein of the Type III Secretion System Encoded by Salmonella Pathogenicity Island 2

2009 ◽  
Vol 191 (22) ◽  
pp. 6843-6854 ◽  
Author(s):  
Tsuyoshi Miki ◽  
Yoshio Shibagaki ◽  
Hirofumi Danbara ◽  
Nobuhiko Okada
Keyword(s):  
Protein Interactions ◽  
Type Iii Secretion ◽  
Functional Characterization ◽  
Coiled Coil ◽  
Type Iii Secretion System ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT The type III secretion system (T3SS) encoded by Salmonella pathogenicity island 2 (SPI-2) is involved in systemic infection and intracellular replication of Salmonella enterica serovar Typhimurium. In this study, we investigated the function of SsaE, a small cytoplasmic protein encoded within the SPI-2 locus, which shows structural similarity to the T3SS class V chaperones. An S. enterica serovar Typhimurium ssaE mutant failed to secrete SPI-2 translocator SseB and SPI-2-dependent effector PipB proteins. Coimmunoprecipitation and mass spectrometry analyses using an SsaE-FLAG fusion protein indicated that SsaE interacts with SseB and a putative T3SS-associated ATPase, SsaN. A series of deleted and point-mutated SsaE-FLAG fusion proteins revealed that the C-terminal coiled-coil domain of SsaE is critical for protein-protein interactions. Although SseA was reported to be a chaperone for SseB and to be required for its secretion and stability in the bacterial cytoplasm, an sseA deletion mutant was able to secrete the SseB in vitro when plasmid-derived SseB was overexpressed. In contrast, ssaE mutant strains could not transport SseB extracellularly under the same assay conditions. In addition, an ssaE(I55G) point-mutated strain that expresses the SsaE derivative lacking the ability to form a C-terminal coiled-coil structure showed attenuated virulence comparable to that of an SPI-2 T3SS null mutant, suggesting that the coiled-coil interaction of SsaE is absolutely essential for the functional SPI-2 T3SS and for Salmonella virulence. Based on these findings, we propose that SsaE recognizes translocator SseB and controls its secretion via SPI-2 type III secretion machinery.

scholarly journals Characterization of the cis-Acting Regulatory Element Controlling HrpB-Mediated Activation of the Type III Secretion System and Effector Genes in Ralstonia solanacearum

2004 ◽  
Vol 186 (8) ◽  
pp. 2309-2318 ◽  
Author(s):  
Sébastien Cunnac ◽  
Christian Boucher ◽  
Stéphane Genin
Keyword(s):  
Ralstonia Solanacearum ◽  
Type Iii Secretion ◽  
Xanthomonas Campestris ◽  
Consensus Sequence ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Site Directed Mutagenesis ◽  
Critical Parameters ◽  
Type Iii ◽  
Regulated Promoters

ABSTRACT The ability of Ralstonia solanacearum to cause disease on plants depends on its type III secretion system (TTSS) encoded by hrp genes. The expression of hrp genes and known TTSS substrates is coordinately regulated by HrpB, a member of the AraC family of transcriptional regulators. Two HrpB-regulated promoters (hrpY and popABC) were characterized by deletion analysis, and the HrpB-dependent activation of these promoters was found to be conferred by a 25-nucleotide DNA element, the hrp II box (TTCGn16TTCG), which is present in other hrp promoters. The hrp II box element is an imperfect plant inducible promoter box, an element which was originally found in hrp promoters of Xanthomonas campestris (S. Fenselau and U. Bonas, Mol. Plant-Microbe Interact. 8:845-854, 1995) but which was not characterized at the molecular level. Site-directed mutagenesis showed that the hrp II box is essential for hrpY promoter activation in vivo. Functional analysis of the hrp II box element identified critical parameters that are required for HrpB-dependent activity. Further mapping analyses of several other hrpB-dependent promoters also indicated that the position of the hrp II box is conserved, at −70 to −47 bp from the transcriptional start. As a first step toward identifying novel TTSS effectors, we used the hrp II box consensus sequence to search for potential HrpB-regulated promoters in the complete genome sequence of R. solanacearum strain GMI1000. Among the 114 genes identified, a subset of promoters was found to have a structural relationship with hrp promoters, thus providing a pool of candidate genes encoding TTSS effectors.

scholarly journals Naturally Occurring Nonpathogenic Isolates of the Plant Pathogen Pseudomonas syringae Lack a Type III Secretion System and Effector Gene Orthologues

2008 ◽  
Vol 190 (8) ◽  
pp. 2858-2870 ◽  
Author(s):  
Toni J. Mohr ◽  
Haijie Liu ◽  
Shuangchun Yan ◽  
Cindy E. Morris ◽  
José A. Castillo ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Plant Cells ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Plant Diseases ◽  
In Planta ◽  
Type Iii ◽  
Effector Gene

ABSTRACT Pseudomonas syringae causes plant diseases, and the main virulence mechanism is a type III secretion system (T3SS) that translocates dozens of effector proteins into plant cells. Here we report the existence of a subgroup of P. syringae isolates that do not cause disease on any plant species tested. This group is monophyletic and most likely evolved from a pathogenic P. syringae ancestor through loss of the T3SS. In the nonpathogenic isolate P. syringae 508 the genomic region that in pathogenic P. syringae strains contains the hrp-hrc cluster coding for the T3SS and flanking effector genes is absent. P. syringae 508 was also surveyed for the presence of effector orthologues from the closely related pathogenic strain P. syringae pv. syringae B728a, but none were detected. The absence of the hrp-hrc cluster and effector orthologues was confirmed for other nonpathogenic isolates. Using the AvrRpt2 effector as reporter revealed the inability of P. syringae 508 to translocate effectors into plant cells. Adding a plasmid-encoded T3SS and the P. syringae pv. syringae 61 effector gene hopA1 increased in planta growth almost 10-fold. This suggests that P. syringae 508 supplemented with a T3SS could be used to determine functions of individual effectors in the context of a plant infection, avoiding the confounding effect of other effectors with similar functions present in effector mutants of pathogenic isolates.

scholarly journals Identification and functional characterization of EseH, a new effector of the type III secretion system ofEdwardsiella piscicida

2016 ◽  
Vol 19 (1) ◽  
pp. e12638 ◽  
Author(s):  
Mingyu Hou ◽  
Ran Chen ◽  
Dahai Yang ◽  
Gabriel Núñez ◽  
Zhuang Wang ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Functional Characterization ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii
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