Functional characterization and proteomic analysis of lolA in Xanthomonas campestris pv. campestris

Abstract

BackgroundThe gram-negative Xanthomonas campestris pv. campestris is the pathogenic bacterium that causes black rot disease in crucifers. The virulence determinants of this bacterium include extracellular enzymes, exopolysaccharides, and biofilm formation. Here, one transposon mutant of X. campestris pv. campestris strain 17 that affects biofilm formation was isolated, and subsequent analyses led to the identification of the lolA gene, which encodes an outer membrane lipoprotein chaperone.ResultsThe lolA mutant exhibited significant reductions in bacterial attachment, extracellular enzyme production, virulence, and tolerance in the presence of myriad membrane-perturbing agents. These phenotypic changes of the mutant could be complemented to the wild-type level through the intact lolA gene. Proteomic analysis revealed that 109 proteins were differentially expressed after lolA mutation. These differentially expressed proteins were categorized in various functional groups and were mainly associated with the membrane component, were involved in transport, and contained receptor activity. Through reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) analysis, deletion of lolA was determined to have caused significantly reduced expression of genes that encode the major extracellular enzymes, the biofilm-related proteins, and the virulence-related proteins. The RT-qPCR analysis also indicated that the expression of several genes that encode putative outer membrane lipoproteins and TonB-dependent receptors was reduced after lolA mutation.ConclusionsThis is the first report to define the lolA gene as a virulence factor and to contribute to the functional understanding of, and provide new information concerning, the role of lolA in Xanthomonas. Furthermore, the results of this study provide and extend new insights into the function of lolA in bacteria.Electronic supplementary materialThe online version of this article (10.1186/s12866-019-1387-9) contains supplementary material, which is available to authorized users.

Genome-Wide Identification of Ralstonia solanacearum Genes Required for Survival in Tomato Plants

“…The absence of LolA in the plant pathogen Xanthomonas campestris pv. campestris reduced the pathogen’s attachment, extracellular enzyme production, and virulence ( 22 ). As shown in Fig.…”

Biogenesis of Type V pili

“…The lolA gene is essential in E. coli and Pseudomonas aeruginosa , 100,101 whereas it is nonessential in Helicobacter pylori , 102 Flavobacterium johnsoniae , 103 Cellulophaga algicola , 104 or Xanthomonas campestris pv. campestris , 105 as evidenced by the successful generation of respective lolA ‐deficient mutants. Notably, in E. coli , both lolA ‐ and lolB ‐deficient mutants can be generated in the genetic background with lpp and rcsB mutations and the activating Cpx envelope stress response 106 .…”

Antibiofilm Activity of a Trichoderma Metabolite against Xanthomonas campestris pv. campestris, Alone and in Association with a Phage

“…campestris ( Xcc ) is the causal agent of black-rot disease in crucifers, responsible for serious yield losses worldwide [ 1 ]. The bacterial secretion composed of exopolysaccharides can obstruct the xylem vessels, causing tissue necrosis and leaf wilting [ 2 ]. The Xcc produces a variety of substances, such as enzymes, that may be used by this bacterium to parasitize the host [ 3 ].…”