title: Proteomic analysis reveals novel extracellular virulence-associated proteins and functions regulated by the diffusible signal factor (DSF) in Xanthomonas oryzae pv. oryzicola.
abstract: Quorum sensing (QS) in Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of bacterial leaf streak, is mediated by the diffusible signal factor (DSF). DSF-mediating QS has been shown to control virulence and a set of virulence-related functions; however, the expression profiles and functions of extracellular proteins controlled by DSF signal remain largely unclear. In the present study, 33 DSF-regulated extracellular proteins, whose functions include small-protein mediating QS, oxidative adaptation, macromolecule metabolism, cell structure, biosynthesis of small molecules, intermediary metabolism, cellular process, protein catabolism, and hypothetical function, were identified by proteomics in Xoc. Of these, 15 protein encoding genes were in-frame deleted, and 4 of them, including three genes encoding type II secretion system (T2SS)-dependent proteins and one gene encoding an Ax21 (activator of XA21-mediated immunity)-like protein (a novel small-protein type QS signal) were determined to be required for full virulence in Xoc. The contributions of these four genes to important virulence-associated functions, including bacterial colonization, extracellular polysaccharide, cell motility, biofilm formation, and antioxidative ability, are presented. To our knowledge, our analysis is the first complete list of DSF-regulated extracellular proteins and functions in a Xanthomonas species. Our results show that DSF-type QS played critical roles in regulation of T2SS and Ax21-mediating QS, which sheds light on the role of DSF signaling in Xanthomonas.
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Qian
authors.forename: Yijing
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yancun
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Song
authors.forename: Suyan
authors.initials: S
authors.lastname: Wang
authors.forename: Jiaqin
authors.initials: J
authors.lastname: Fan
authors.forename: Baishi
authors.initials: B
authors.lastname: Hu
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
authors.forename: Fengquan
authors.initials: F
authors.lastname: Liu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D012275:Oryza / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D040901:Proteomics / Q000379:methods*; D053038:Quorum Sensing / Q000235:genetics*; D015398:Signal Transduction; D014774:Virulence / Q000235:genetics; D014974:Xanthomonas / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins