title: Pantoea ananatis Utilizes a Type VI Secretion System for Pathogenesis and Bacterial Competition.
abstract: Type VI secretion systems (T6SSs) are a class of macromolecular machines that are recognized as an important virulence mechanism in several gram-negative bacteria. The genome of Pantoea ananatis LMG 2665(T), a pathogen of pineapple fruit and onion plants, carries two gene clusters whose predicted products have homology with T6SS-associated gene products from other bacteria. Nothing is known regarding the role of these T6SS-1 and T6SS-3 gene clusters in the biology of P. ananatis. Here, we present evidence that T6SS-1 plays an important role in the pathogenicity of P. ananatis LMG 2665(T) in onion plants, while a strain lacking T6SS-3 remains as pathogenic as the wild-type strain. We also investigated the role of the T6SS-1 system in bacterial competition, the results of which indicated that several bacteria compete less efficiently against wild-type LMG 2665(T) than a strain lacking T6SS-1. Additionally, we demonstrated that these phenotypes of strain LMG 2665(T) were reliant on the core T6SS products TssA and TssD (Hcp), thus indicating that the T6SS-1 gene cluster encodes a functioning T6SS. Collectively, our data provide the first evidence demonstrating that the T6SS-1 system is a virulence determinant of P. ananatis LMG 2665(T) and plays a role in bacterial competition.
authors.affiliation: 1 Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Sciences, and.
authors.forename: Divine Y
authors.initials: DY
authors.lastname: Shyntum
authors.forename: Jacques
authors.initials: J
authors.lastname: Theron
authors.forename: Stephanus N
authors.initials: SN
authors.lastname: Venter
authors.forename: Lucy N
authors.initials: LN
authors.lastname: Moleleki
authors.forename: Ian K
authors.initials: IK
authors.lastname: Toth
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Coutinho
mesh_terms: D058947:Bacterial Secretion Systems / Q000235:genetics* / Q000502:physiology; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D054884:Host-Pathogen Interactions / Q000235:genetics* / Q000502:physiology; D005810:Multigene Family; D009154:Mutation; D019697:Onions / Q000382:microbiology; D020636:Pantoea / Q000235:genetics* / Q000472:pathogenicity* / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D014774:Virulence / Q000235:genetics* / Q000502:physiology
chemical_list: D058947:Bacterial Secretion Systems