title: Translocation and functional analysis of Pseudomonas savastanoi pv. savastanoi NCPPB 3335 type III secretion system effectors reveals two novel effector families of the Pseudomonas syringae complex.
abstract: Pseudomonas savastanoi pv. savastanoi NCPPB 3335 causes olive knot disease and is a model pathogen for exploring bacterial infection of woody hosts. The type III secretion system (T3SS) effector repertoire of this strain includes 31 effector candidates plus two novel candidates identified in this study which have not been reported to translocate into plant cells. In this work, we demonstrate the delivery of seven NCPPB 3335 effectors into Nicotiana tabacum leaves, including three proteins from two novel families of the P. syringae complex effector super-repertoire (HopBK and HopBL), one of which comprises two proteins (HopBL1 and HopBL2) that harbor a SUMO protease domain. When delivered by P. fluorescens heterologously expressing a P. syringae T3SS, all seven effectors were found to suppress the production of defense-associated reactive oxygen species. Moreover, six of these effectors, including the truncated versions of HopAA1 and HopAZ1 encoded by NCPPB 3335, suppressed callose deposition. The expression of HopAZ1 and HopBL1 by functionally effectorless P. syringae pv. tomato DC3000D28E inhibited the hypersensitive response in tobacco and, additionally, expression of HopBL2 by this strain significantly increased its competitiveness in N. benthamiana. DNA sequences encoding HopBL1 and HopBL2 were uniquely detected in a collection of 31 P. savastanoi pv. savastanoi strains and other P. syringae strains isolated from woody hosts, suggesting a relevant role of these two effectors in bacterial interactions with olive and other woody plants.
authors: Isabel M
authors: IM
authors: Matas
authors: M Pilar
authors: MP
authors: Castañeda-Ojeda
authors: Isabel M
authors: IM
authors: Aragón
authors: María
authors: M
authors: Antúnez-Lamas
authors: Jesús
authors: J
authors: Murillo
authors: Pablo
authors: P
authors: Rodríguez-Palenzuela
authors: Emilia
authors: E
authors: López-Solanilla
authors: Cayo
authors: C
authors: Ramos
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000235:genetics; D001692:Biological Transport; D019295:Computational Biology; D015964:Gene Expression Regulation, Bacterial; D005936:Glucans / Q000378:metabolism; D054884:Host-Pathogen Interactions; D009154:Mutation; D031658:Olea / Q000382:microbiology*; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D017434:Protein Structure, Tertiary; D011549:Pseudomonas / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D005936:Glucans; D017382:Reactive Oxygen Species; C048306:callose