A two-component system in Ralstonia (Pseudomonas) solanacearum modulates production of PhcA-regulated virulence factors in response to 3- hydroxypalmitic acid methyl ester

Steven J Clough, Kim Eng Lee, Mark A. Schell, Timothy P. Denny

Research output: Contribution to journalArticle

Abstract

Expression of virulence factors in Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA, a LysR family transcriptional regulator. We report here that expression of phcA and production of PhcA-regulated virulence factors are affected by products of the putative operon phcBSR(Q). phcB is required for production of an extracellular factor (EF), tentatively identified as the fatty acid derivative 3-hydroxypalmitic acid methyl ester (3-OH PAME), but a biochemical function for PhcB could not be deduced from DNA sequence analysis. The other genes in the putative operon are predicted to encode proteins homologous to members of two-component signal transduction systems: PhcS has amino acid similarity to histidine kinase sensors, whereas PhcR and OrfQ are similar to response regulators. PhcR is quite unusual because its putative output domain strongly resembles the histidine kinase domain of a sensor protein. Production of the PhcA-regulated factors exopolysaccharide L endoglucanase, and pectin methyl esterase was reduced 10- to 100-fold only in mutants with a nonpolar insertion in phcB [which express phcSR(Q) in the absence of the EF]; simultaneously, expression of phcA was reduced fivefold. Both a wild-type phenotype and phcA expression were restored by addition of 3-OH PAME to growing cultures. Mutants with polar insertions in phcB or lacking the entire phcBSR(Q) region produced wild-type levels of PhcA-regulated virulence factors. The genetic data suggest that PhcS and PhcR function together to regulate expression of phcA, but the biochemical mechanism for this is unclear. At low levels of the EF, it is likely that PhcS phosphorylates PhcR, and then PhcR interacts either with PhcA (which is required for full expression of phcA) or an unknown component of the signal cascade to inhibit expression of phcA. When the EF reaches a threshold concentration, we suggest that it reduces the ability of PhcS to phosphorylate PhcR, resulting in increased expression of phcA and production of PhcA-regulated factors.

Original languageEnglish (US)
Pages (from-to)3639-3648
Number of pages10
JournalJournal of bacteriology
Volume179
Issue number11
DOIs
StatePublished - Jun 1997

Fingerprint

Ralstonia solanacearum
Virulence Factors
Esters
Operon
Cellulase
DNA Sequence Analysis
Signal Transduction
Proteins
Fatty Acids
Phenotype
Amino Acids
Genes
3-hydroxypalmitic acid
Histidine Kinase
1-phenyl-1-aminomethylethene

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Cite this

A two-component system in Ralstonia (Pseudomonas) solanacearum modulates production of PhcA-regulated virulence factors in response to 3- hydroxypalmitic acid methyl ester. / Clough, Steven J; Lee, Kim Eng; Schell, Mark A.; Denny, Timothy P.

In: Journal of bacteriology, Vol. 179, No. 11, 06.1997, p. 3639-3648.

Research output: Contribution to journalArticle

@article{977ad95e4a984df196c63b37decbb70d,
title = "A two-component system in Ralstonia (Pseudomonas) solanacearum modulates production of PhcA-regulated virulence factors in response to 3- hydroxypalmitic acid methyl ester",
abstract = "Expression of virulence factors in Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA, a LysR family transcriptional regulator. We report here that expression of phcA and production of PhcA-regulated virulence factors are affected by products of the putative operon phcBSR(Q). phcB is required for production of an extracellular factor (EF), tentatively identified as the fatty acid derivative 3-hydroxypalmitic acid methyl ester (3-OH PAME), but a biochemical function for PhcB could not be deduced from DNA sequence analysis. The other genes in the putative operon are predicted to encode proteins homologous to members of two-component signal transduction systems: PhcS has amino acid similarity to histidine kinase sensors, whereas PhcR and OrfQ are similar to response regulators. PhcR is quite unusual because its putative output domain strongly resembles the histidine kinase domain of a sensor protein. Production of the PhcA-regulated factors exopolysaccharide L endoglucanase, and pectin methyl esterase was reduced 10- to 100-fold only in mutants with a nonpolar insertion in phcB [which express phcSR(Q) in the absence of the EF]; simultaneously, expression of phcA was reduced fivefold. Both a wild-type phenotype and phcA expression were restored by addition of 3-OH PAME to growing cultures. Mutants with polar insertions in phcB or lacking the entire phcBSR(Q) region produced wild-type levels of PhcA-regulated virulence factors. The genetic data suggest that PhcS and PhcR function together to regulate expression of phcA, but the biochemical mechanism for this is unclear. At low levels of the EF, it is likely that PhcS phosphorylates PhcR, and then PhcR interacts either with PhcA (which is required for full expression of phcA) or an unknown component of the signal cascade to inhibit expression of phcA. When the EF reaches a threshold concentration, we suggest that it reduces the ability of PhcS to phosphorylate PhcR, resulting in increased expression of phcA and production of PhcA-regulated factors.",
author = "Clough, {Steven J} and Lee, {Kim Eng} and Schell, {Mark A.} and Denny, {Timothy P.}",
year = "1997",
month = "6",
doi = "10.1128/jb.179.11.3639-3648.1997",
language = "English (US)",
volume = "179",
pages = "3639--3648",
journal = "Journal of Bacteriology",
issn = "0021-9193",
publisher = "American Society for Microbiology",
number = "11",

}

TY - JOUR

T1 - A two-component system in Ralstonia (Pseudomonas) solanacearum modulates production of PhcA-regulated virulence factors in response to 3- hydroxypalmitic acid methyl ester

AU - Clough, Steven J

AU - Lee, Kim Eng

AU - Schell, Mark A.

AU - Denny, Timothy P.

PY - 1997/6

Y1 - 1997/6

N2 - Expression of virulence factors in Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA, a LysR family transcriptional regulator. We report here that expression of phcA and production of PhcA-regulated virulence factors are affected by products of the putative operon phcBSR(Q). phcB is required for production of an extracellular factor (EF), tentatively identified as the fatty acid derivative 3-hydroxypalmitic acid methyl ester (3-OH PAME), but a biochemical function for PhcB could not be deduced from DNA sequence analysis. The other genes in the putative operon are predicted to encode proteins homologous to members of two-component signal transduction systems: PhcS has amino acid similarity to histidine kinase sensors, whereas PhcR and OrfQ are similar to response regulators. PhcR is quite unusual because its putative output domain strongly resembles the histidine kinase domain of a sensor protein. Production of the PhcA-regulated factors exopolysaccharide L endoglucanase, and pectin methyl esterase was reduced 10- to 100-fold only in mutants with a nonpolar insertion in phcB [which express phcSR(Q) in the absence of the EF]; simultaneously, expression of phcA was reduced fivefold. Both a wild-type phenotype and phcA expression were restored by addition of 3-OH PAME to growing cultures. Mutants with polar insertions in phcB or lacking the entire phcBSR(Q) region produced wild-type levels of PhcA-regulated virulence factors. The genetic data suggest that PhcS and PhcR function together to regulate expression of phcA, but the biochemical mechanism for this is unclear. At low levels of the EF, it is likely that PhcS phosphorylates PhcR, and then PhcR interacts either with PhcA (which is required for full expression of phcA) or an unknown component of the signal cascade to inhibit expression of phcA. When the EF reaches a threshold concentration, we suggest that it reduces the ability of PhcS to phosphorylate PhcR, resulting in increased expression of phcA and production of PhcA-regulated factors.

AB - Expression of virulence factors in Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA, a LysR family transcriptional regulator. We report here that expression of phcA and production of PhcA-regulated virulence factors are affected by products of the putative operon phcBSR(Q). phcB is required for production of an extracellular factor (EF), tentatively identified as the fatty acid derivative 3-hydroxypalmitic acid methyl ester (3-OH PAME), but a biochemical function for PhcB could not be deduced from DNA sequence analysis. The other genes in the putative operon are predicted to encode proteins homologous to members of two-component signal transduction systems: PhcS has amino acid similarity to histidine kinase sensors, whereas PhcR and OrfQ are similar to response regulators. PhcR is quite unusual because its putative output domain strongly resembles the histidine kinase domain of a sensor protein. Production of the PhcA-regulated factors exopolysaccharide L endoglucanase, and pectin methyl esterase was reduced 10- to 100-fold only in mutants with a nonpolar insertion in phcB [which express phcSR(Q) in the absence of the EF]; simultaneously, expression of phcA was reduced fivefold. Both a wild-type phenotype and phcA expression were restored by addition of 3-OH PAME to growing cultures. Mutants with polar insertions in phcB or lacking the entire phcBSR(Q) region produced wild-type levels of PhcA-regulated virulence factors. The genetic data suggest that PhcS and PhcR function together to regulate expression of phcA, but the biochemical mechanism for this is unclear. At low levels of the EF, it is likely that PhcS phosphorylates PhcR, and then PhcR interacts either with PhcA (which is required for full expression of phcA) or an unknown component of the signal cascade to inhibit expression of phcA. When the EF reaches a threshold concentration, we suggest that it reduces the ability of PhcS to phosphorylate PhcR, resulting in increased expression of phcA and production of PhcA-regulated factors.

UR - http://www.scopus.com/inward/record.url?scp=0030917808&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030917808&partnerID=8YFLogxK

U2 - 10.1128/jb.179.11.3639-3648.1997

DO - 10.1128/jb.179.11.3639-3648.1997

M3 - Article

C2 - 9171411

AN - SCOPUS:0030917808

VL - 179

SP - 3639

EP - 3648

JO - Journal of Bacteriology

JF - Journal of Bacteriology

SN - 0021-9193

IS - 11

ER -