Xanthomonas campestris pv. vesicatoria (Xcv) is the causal agent of a bacterial leaf spot disease, which is one of the most serious bacterial diseases affecting pepper and tomato. This study evaluated the role of wxcB gene in Xcv. The virulence of wxcB gene knockout mutant was weaker than that of the wild type in tomato plants. The protein expression of wild type and wxcB mutant was compared and 152 proteins showed a greater then 2-fold difference. Among them, protein involved in motility and cell wall/membrane were the most abundant. Through phenotypic evaluation, the wxcB mutant revealed reduced motility and tolerance to detergent treatment, but it showed increased biofilm formation. These results gave new insights into the functions of wxcB that is associated with cell wall/membrane functions, which contributes to pathogen virulence.