Regulation of tabtoxin production by the lemA gene in Pseudomonas syringae

Barta, T. M.; Kinscherf, Thomas G.; Willis, David K.

doi:10.1128/jb.174.9.3021-3029.1992

Cited by 61 publications

(49 citation statements)

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“…coronafaciens. Our results show that an active lemA gene is required for the presence of a transcript from a gene in the tabtoxin biosynthetic region (2). Taken together with the data presented here demonstrating that the lemA gene resembles genes encoding two-component regulatory proteins, these results support the hypothesis that the lemA gene encodes a regulatory protein in P. syringae pv.…”

Section: Discussionsupporting

confidence: 80%

“…Some bacterial signal transduction systems seem to have developed similar mechanisms for self-regulation. For example, the bvg locus of B. pertussis has a low level of constitutive expression but can be activated to higher levels of expression by the product of one of the bvg genes (39), resulting in increased expression of bvg-regulated genes (38 (2,35,36). This result suggests that the lemA gene product is not protease and most likely does not function in the biosynthesis of syringomycin.…”

Section: Discussionmentioning

confidence: 99%

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The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

1992

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The lemA gene of the plant pathogen Pseudomonas syringae pv. syringae is required for disease lesion formation on bean plants. Cosmid clones that complemented a lemA mutant in trans were isolated previously. The lemA gene was localized by subcloning and transposon mutagenesis. The lemA region and flanking DNA were sequenced, and an open reading frame of 2.7 kb was identified. The nucleotide and predicted amino acid sequences of the kmA gene showed sequence similarity to a family of prokaryotic two-component regulatory proteins. Unlike most of the previously described two-component systems, the lemA gene product contained homology to both components in one protein. Pseudomonas syringae pv. syringae isolate B728a is a causal agent of bacterial brown spot of bean (Phaseolus vulgaris). To identify bacterial genes necessary for disease development, prototrophic Tn5 mutants of isolate B728a were screened on bean pods for loss of the typical pathogenic response. One mutant, NPS3136, has lost the ability to form brown spot lesions on bean leaves and pods (55). This lemA (lesion manifestation) mutant retains the ability to grow on and colonize bean plants and to elicit a hypersensitive reaction on nonhosts (55). The phenotype of a lemA mutant is significantly different from the phenotype of another class of nonpathogenic mutants, the hrp mutants, which are affected both in their colonization of and pathogenic interaction with host plants and in their ability to elicit a hypersensitive reaction on nonhost plants (for a review, see reference 56). Further characterization of the lemA mutant revealed that it was also deficient in the ability to produce protease and the toxin syringomycin (19,20). This pleiotropic phenotype suggested that the lemA gene might encode a regulatory molecule. In this report, we describe further characterization of the lemA gene of P. syringae pv. syringae by subcloning, transposon mutagenesis, and DNA sequence analysis. We present evidence that the lemA gene has similarity to the conserved domains within both the HPK and the RR proteins in a family of prokaryotic two-component regulatory proteins. MATERIALS AND METHODSBacterial strains, plasmids, and growth conditions. The bacterial strains and plasmids used in this work are listed in

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

1992

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“…glycinea PG4180 was isolated as described by Staskawicz et al (34) and purified on CsCl-EtBr gradients (35). A PG4180 genomic library was constructed in pRK7813 as described previously (36), and Tc r E. coli transfectants were screened by colony hybridization.…”

Section: Methodsmentioning

confidence: 99%

The Pseudomonas syringae Genome Encodes a Combined Mannuronan C-5-epimerase and O-Acetylhydrolase, Which Strongly Enhances the Predicted Gel-forming Properties of Alginates

Bjerkan

Bender

Ertesvåg

et al. 2004

Journal of Biological Chemistry

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Alginates are industrially important, linear copolymers of ␤-D-mannuronic acid (M) and its C-5-epimer ␣-Lguluronic acid (G). The G residues originate from a postpolymerization reaction catalyzed by mannuronan C-5-epimerases (MEs), leading to extensive variability in M/G ratios and distribution patterns. Alginates containing long continuous stretches of G residues (G blocks) can form strong gels, a polymer type not found in alginate-producing bacteria belonging to the genus Pseudomonas. Here we show that the Pseudomonas syringae genome encodes a Ca 2؉ -dependent ME (PsmE) that efficiently forms such G blocks in vitro. The deduced PsmE protein consists of 1610 amino acids and is a modular enzyme related to the previously characterized family of Azotobacter vinelandii ME (AlgE1-7). A-and R-like modules with sequence similarity to those in the AlgE enzymes are found in PsmE, and the A module of PsmE (PsmEA) was found to be sufficient for epimerization. Interestingly, an R module from AlgE4 stimulated PsmEA activity. PsmE contains two regions designated M and RTX, both presumably involved in the binding of Ca 2؉ . Bacterial alginates are partly acetylated, and such modified residues cannot be epimerized. Based on a detailed computer-assisted analysis and experimental studies another PsmE region, designated N, was found to encode an acetylhydrolase. By the combined action of N and A PsmE was capable of redesigning an extensively acetylated alginate low in G from a non gel-forming to a gel-forming state. Such a property has to our knowledge not been previously reported for an enzyme acting on a polysaccharide.

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“…As is the case for many other plant and animal pathogens, P. syringae secretes a variety of products, including quorum-sensing compounds, phytotoxins, antibiotics, exoproteases, fluorescent pigments, and alginate, which influence infection and disease processes (363). These secreted products as well as biofilm formation, host colonization, and lesion formation are all regulated by the GacS/GacA TCS (364)(365)(366)(367)(368)(369)(370)(371)(372)(373)(374)(375)(376)(377)(378)(379). Furthermore, genetic analyses of various P. syringae pathovars have identified homologs of the RsmA-inhibitory sRNAs RsmX, RsmY, and RsmZ of P. fluorescens, as well as RsmB of P. carotovorum (55).…”

Section: Plant Pathogensmentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

302

400

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SUMMARY Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5′ untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens.

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Regulation of tabtoxin production by the lemA gene in Pseudomonas syringae

Cited by 61 publications

References 48 publications

The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

The Pseudomonas syringae Genome Encodes a Combined Mannuronan C-5-epimerase and O-Acetylhydrolase, Which Strongly Enhances the Predicted Gel-forming Properties of Alginates

Regulation of Bacterial Virulence by Csr (Rsm) Systems

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