The PmrA‐PmrB two‐component system responding to acidic pH and iron controls virulence in the plant pathogen Erwinia carotovora ssp. carotovora

Abstract

SummaryEfficient response to environmental cues is crucial to successful infection by plant-pathogenic bacteria such as Erwinia carotovora ssp. carotovora . The expression of the main virulence genes of this pathogen, encoding extracellular enzymes that degrade the plant-cell wall, is subject to complex regulatory machinery where two-component systems play an important role. In this paper, we describe for the first time the involvement of the PmrA-PmrB twocomponent system in regulation of virulence in a plant-pathogenic bacterium. Disruption of pmrB resulted in reduced virulence both in potato and in Arabidopsis . This is apparently due to reduced production of the extracellular enzymes. In contrast, a pmrA mutant exhibited increased levels of these enzymes implying negative regulation of the corresponding genes by PmrA. Furthermore, the pmrB but not pmrA mutant exhibited highly increased resistance to the cationic antimicrobial peptide polymyxin B suggesting alterations in cell surface properties of the mutant. A similar increase of polymyxin resistance was detected in the wild type at mildly acidic pH with low Mg 2+ + + + . Functional pmrA is essential for bacterial survival on excess iron at acidic pH, regardless of the Mg 2+ + + + concentration. We propose that PmrAPmrB TCS is involved in controlling of bacterial response to external pH and iron and is crucial for bacterial virulence and survival in planta .

The RssAB Two-Component Signal Transduction System in Serratia marcescens Regulates Swarming Motility and Cell Envelope Architecture in Response to Exogenous Saturated Fatty Acids

“…Orf2 exhibits homology with two-component response-regulator elements, including 39% identity and 57% homology throughout the alignment to the two-component response regulator PmrA of Pectobacterium carotovorum subsp. carotovorum (19). We designated orf1 rssA (regulation of Serratia swarming A), and orf2 was designated rssB.…”

Characterization of the Genome, Proteome, and Structure of Yersiniophage ϕR1-37

“…Chloramphenicol (20 g ml Ϫ1 ) or ampicillin (150 g ml Ϫ1 ) was added to the media when required. For the preparation of R1-37 for cryo-electron microscopy (cryo-EM) studies, R1-37 phage particles were prepared as described previously (21). Alternatively, cell debris from 500 ml of Y. enterocolitica O:3 strain YeO3-R1 infected with R1-37 was pelleted by low-speed centrifugation (Sorvall SLA-1500 rotor) (8,500 rpm, 20 min, 4°C).…”

“…The YeO3-R1 culture was grown to the logarithmic phase, and after removing a sample for RNA isolation (time zero), the bacteria were infected with R1-37 (MOI value of 1), and the R1-37-infected samples were taken at 7-min intervals up to 42 min total duration. Total RNA was isolated as described previously (3,21). Five to 10 g of total RNA was denatured for 30 min at 50°C with glyoxal load dye (NorthernMax-Gly; Ambion), and electrophoresis was performed according to the manufacturer's instructions.…”

A Novel Plant Ferredoxin-Like Protein and the Regulator Hor Are Quorum-Sensing Targets in the Plant Pathogen Erwinia carotovora

“…Northern blot analysis was performed with 10 μg of total RNA separated in 1.5% formaldehyde gel. Specific digoxigenin-labeled DNA fragments for the Northern blots were amplified with PCR using the following primers: ferE (Fw) 5′-GCTCATCATCTAAAAAAGACTGATC-3′ and (Rev) 5′-GAT ATAGAGTGCTCCGATGATG-3′ and hor (Fw) 5′-TGCAATC CAGGGATATAAC-3′ and (Rev) 5′-GTTATGCAACGTGACC CA-3′; and 16S rRNA primers F2115 and F2116 (Hyytiäinen et al 2003). The blotting hybridization and digoxigenin detection was performed according to the manufacturer's instructions (Roche, Diagnostics, Basel, Switzerland).…”