The galU gene of Xanthomonas campestris pv. campestris is involved in bacterial attachment, cell motility, polysaccharide synthesis, virulence, and tolerance to various stresses

Abstract

Uridine triphosphate (UTP)-glucose-1-phosphate uridylyltransferase (GalU; EC 2.7.7.9) is an enzyme that catalyzes the formation of uridine diphosphate (UDP)-glucose from UTP and glucose-1-phosphate. GalU is involved in virulence in a number of animal-pathogenic bacteria since its product, UDP-glucose, is indispensable for the biosynthesis of virulence factors such as lipopolysaccharide and exopolysaccharide. However, its function in Xanthomonas campestris pv. campestris, the phytopathogen that causes black rot in cruciferous plants, is unclear. Here, we characterized a galU mutant of X. campestris pv. campestris and showed that the X. campestris pv. campestris galU mutant resulted in a reduction in virulence on the host cabbage. We also demonstrated that galU is involved in bacterial attachment, cell motility, and polysaccharide synthesis. Furthermore, the galU mutant showed increased sensitivity to various stress conditions including copper sulfate, hydrogen peroxide, and sodium dodecyl sulfate. In addition, mutation of galU impairs the expression of the flagellin gene fliC as well as the attachment-related genes xadA, fhaC, and yapH. In conclusion, our results indicate involvement of galU in the virulence factor production and pathogenicity in X. campestris pv. campestris, and a role for galU in stress tolerance of this crucifer pathogen.

UDP-glucose pyrophosphorylase influences polysaccharide synthesis, cell wall components, and hyphal branching in Ganoderma lucidum via regulation of the balance between glucose-1-phosphate and UDP-glucose

“…Furthermore, the sensitivity of the ugpi strains to SDS was increased, possibly due to reduced EPS production. These results are similar to those that have been reported for bacteria, demonstrating that EPS can protect bacteria against the anionic hydrophobic agent SDS (Liao et al, 2014). In our study, we found that the ugpi strains had thicker and mostly electron-transparent cell walls, similar to results that have been reported for an Aspergillus nidulans UDP-sugar transporter mutant (Afroz et al, 2011).…”

“…In previous studies, the ugp gene has been shown to be associated with the syntheses of the surface structures LPS and EPS (Jiang et al, 2010;Liao et al, 2014) because its substrate/product UDP-Glc is the precursor of these polysaccharides. Both EPS and IPS were detected in the ugpi and WT strains.…”

“…In bacteria, the ugp gene is also involved in multiple polysaccharide biosynthesis pathways (Valla et al, 1989). Furthermore, it has been reported that it can regulate the formation of biofilms and the associated virulence of some species of bacteria due to its effects on polysaccharide biosynthesis (Guo et al, 2010;Liao et al, 2014).…”

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

“…vesicatoria wxcB , X. citri subsp. citri gpsX , nlxA , and wxacO , and Xcc galU and xagB , play a role in environmental stress tolerance. All of these genes are also important for lipopolysaccharide synthesis except for wxcB .…”

“…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.…”