title: An antimicrobial protein of the Riptortus pedestris salivary gland was cleaved by a virulence factor of Serratia marcescens.
abstract: Recently, our group demonstrated that the bean bug, Riptortus pedestris, is a good experimental symbiosis model to study the molecular cross-talk between the host insect and the gut symbiont. The Burkholderia symbiont is orally acquired by host nymphs from the environment in every generation. However, it is still unclear how Riptortus specifically interacts with entomopathogens that are abundant in the environmental soil. In preliminary experiments, we observed that a potent entomopathogen, Serratia marcescens, can colonize the midgut of Riptortus insects and was recovered from the midgut when Serratia cells were orally administered, suggesting that this pathogenic bacterium can escape host immune defenses in the salivary fluid. We examined how orally fed Serratia cells can survive in the presence of antimicrobial substances of the Riptortus salivary fluid. In this study, a 15 kDa trialysin-like protein from the salivary gland of R. pedestris and a potent virulence factor of Serratia cells, a serralysin metalloprotease, from the culture medium of S. marcescens were successfully purified to homogeneity. When the purified Riptortus trialysin (rip-trialysin) was incubated with purified serralysin, rip-trialysin was specifically hydrolyzed by serralysin, leading to the loss of antimicrobial activity. These results clearly demonstrated that a potent virulent metalloprotease of S. marcescens functions as a key player in the escape from the salivary fluid-mediated host immune response, resulting in successful colonization of S. marcescens in the host midgut.
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Busan 46241, South Korea.
authors.forename: Dong Jung
authors.initials: DJ
authors.lastname: Lee
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Busan 46241, South Korea.
authors.forename: Jun Beom
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Busan 46241, South Korea.
authors.forename: Ho Am
authors.initials: HA
authors.lastname: Jang
authors.affiliation: Equipe Fondation Recherche Médicale, UPR 9022 du CNRS, Institut de Biologie Moleculaire et Cellulaire du CNRS, Strasbourg, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Ferrandon
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Busan 46241, South Korea. Electronic address: brlee@pusan.ac.kr.
authors.forename: Bok Luel
authors.initials: BL
authors.lastname: Lee
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002478:Cells, Cultured; D006430:Hemiptera / Q000276:immunology*; D054884:Host-Pathogen Interactions; D057131:Immune Evasion; D007113:Immunity, Innate; D019476:Insect Proteins / Q000378:metabolism*; D045726:Metalloproteases / Q000378:metabolism; D059748:Proteolysis; D012469:Salivary Glands / Q000276:immunology*; D016868:Serratia Infections / Q000276:immunology*; D012706:Serratia marcescens / Q000276:immunology* / Q000472:pathogenicity; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D019476:Insect Proteins; D037521:Virulence Factors; D045726:Metalloproteases
keywords: Pathogen-host interaction; Rip-trialysin peptide; Riptortus pedestris; Serralysin; Serratia marcescens