title: Insect Gut Symbiont Susceptibility to Host Antimicrobial Peptides Caused by Alteration of the Bacterial Cell Envelope.
abstract: The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis.
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Jiyeun Kate
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Dae Woo
authors.initials: DW
authors.lastname: Son
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Chan-Hee
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Jae Hyun
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, Napoli 80126, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Marchetti
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, Napoli 80126, Italy.
authors.forename: Alba
authors.initials: A
authors.lastname: Silipo
authors.affiliation: CNR-Istituto per i Polimeri, Compositi e Biomateriali IPCB, Via P. Gaifami 18, Catania 95126, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Sturiale
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Ha Young
authors.initials: HY
authors.lastname: Park
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Ye Rang
authors.initials: YR
authors.lastname: Huh
authors.affiliation: Biomolecular Characterization Team, RIKEN Advanced Science Institute, Saitama 351-0198, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakayama
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8566, Japan.
authors.forename: Takema
authors.initials: T
authors.lastname: Fukatsu
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, Napoli 80126, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molinaro
authors.affiliation: Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea. Electronic address: brlee@pusan.ac.kr.
authors.forename: Bok Luel
authors.initials: BL
authors.lastname: Lee
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D019117:Burkholderia / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D020062:Heteroptera / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D019081:O Antigens / Q000737:chemistry* / Q000378:metabolism; D013559:Symbiosis
chemical_list: D023181:Antimicrobial Cationic Peptides; D019081:O Antigens
keywords: Burkholderia; LPS; bean bug; gut symbionts; host defense; host-pathogen interaction; innate immunity; symbiosis