We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Virulence in Pectobacterium atrosepticum is regulated by a coincidence circuit involving quorum sensing and the stress alarmone, (p)pp Gpp.
- Authors
Bowden, Steven D.; Eyres, Alison; Chung, Jade C. S.; Monson, Rita E.; Thompson, Arthur; Salmond, George P. C.; Spring, David R.; Welch, Martin
- Abstract
Pectobacterium atrosepticum ( Pca) is a Gram-negative phytopathogen which causes disease by secreting plant cell wall degrading exoenzymes ( PCWDEs). Previous studies have shown that PCWDE production is regulated by (i) the intercellular quorum sensing ( QS) signal molecule, 3-oxo-hexanoyl- l-homoserine lactone ( OHHL), and (ii) the intracellular 'alarmone', (p)pp Gpp, which reports on nutrient limitation. Here we show that these two signals form an integrated coincidence circuit which ensures that metabolically costly PCWDE synthesis does not occur unless the population is simultaneously quorate and nutrient limited. A (p)pp Gpp null Δ relAΔ spoT mutant was defective in both OHHL and PCWDE production, and nutritional supplementation of wild type cultures (which suppresses (p)pp Gpp production) also suppressed OHHL and PCWDE production. There was a substantial overlap in the transcriptome of a (p)pp Gpp deficient relA mutant and of a QS defective expI ( OHHL synthase) mutant, especially with regards to virulence-associated genes. Random transposon mutagenesis revealed that disruption of rsmA was sufficient to restore PCWDE production in the (p)pp Gpp null strain. We found that the ratio of RsmA protein to its RNA antagonist, rsm B, was modulated independently by (p)pp Gpp and QS. While QS predominantly controlled virulence by modulating RsmA levels, (p)pp Gpp exerted regulation through the modulation of the RsmA antagonist, rsm B.
- Subjects
MICROBIAL virulence; ERWINIA; QUORUM sensing; GRAM-negative bacteria; EXTRACELLULAR enzymes; TRANSPOSONS; MUTAGENESIS; BACTERIA
- Publication
Molecular Microbiology, 2013, Vol 90, Issue 3, p457
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/mmi.12369