Mutation of the gene encoding a major outer-membrane protein in Xanthomonas campestris pv. campestris causes pleiotropic effects, including loss of pathogenicity

Abstract

Xanthomonas cam pestris pv. campestris (Xcc) is the phytopathogen that causes black rot in crucifers. The xanthan polysaccharide and extracellular enzymes produced by this organism are virulence factors, the expression of which is upregulated by Clp (CRP-like protein) and DSF (diffusible signal factor), which is synthesized by RpfF. It is also known that biofilm formation/dispersal, regulated by the effect of controlled synthesis of DSF on cell-cell signalling, is required for virulence. Furthermore, a deficiency in DSF causes cell aggregation with concomitant production of a gum-like substance that can be dispersed by addition of DSF or digested by exogenous endo-beta-1,4-mannanase expressed by Xcc. In this study, Western blotting of proteins from a mopB mutant (XcMopB) showed Xcc MopB to be the major outer-membrane protein (OMP); Xcc MopB shared over 97% identity with homologues from other members of Xanthomonas. Similarly to the rpfF mutant, XcMopB formed aggregates with simultaneous production of a gummy substance, but these aggregates could not be dispersed by DSF or endo-beta-1,4-mannanase, indicating that different mechanisms were involved in aggregation. In addition, XcMopB showed surface deformation, altered OMP composition, impaired xanthan production, increased sensitivity to stressful conditions including SDS, elevated temperature and changes in pH, reduced adhesion and motility and defects in pathogenesis. The finding that the major OMP is required for pathogenicity is unprecedented in phytopathogenic bacteria

Peptidoglycan hydrolysis mediated by the amidase AmiC and its LytM activator NlpD is critical for cell separation and virulence in the phytopathogen Xanthomonas campestris

“…Preparation of the outer and inner membrane proteins was carried out as described by Chen et al . (). Briefly, 100 mL of Xcc cells were grown in NYG medium at 28 °С overnight and collected by centrifugation at 3 488 g at 4 °C for 10 min.…”

“…The bacterial total and periplasmic proteins were prepared by the method reported previously (Zang et al, 2007). Preparation of the outer and inner membrane proteins was carried out as described by Chen et al (2010). Briefly, 100 mL of Xcc cells were grown in NYG medium at 28 8 overnight and collected by centrifugation at 3 488 g at 4 8C for 10 min.…”

WxcX is involved in bacterial attachment and virulence in Xanthomonas campestris pv. campestris

“…Since several factors playing a role in bacterial attachment are involved in pathogenicity in Xcc [12][13][14]17,18], we aimed to determine whether the wxcX gene is associated with the virulence of Xcc. The wxcX mutant revealed reduced virulence compared with the wild type (Fig.…”

Functional properties of the major outer membrane protein in Stenotrophomonas maltophilia

“…The procedures used for fractionation of S. maltophilia were as described previously (Chen et al, 2010). Protein concentrations in Sarkosyl-soluble and Sarkosyl-insoluble fractions were determined using a Bio-Rad detergent-compatible protein assay kit (catalog no.…”

“…campestris, in which the mopB mutant (XcMopB) and parental strains also grow at similar rates prior to the stationary phase, the mopB mutant strain forms obvious aggregates upon entering the stationary phase (Chen et al, 2010). 6B and C).…”