title: A type VI secretion system of Pseudomonas aeruginosa targets a toxin to bacteria.
abstract: The functional spectrum of a secretion system is defined by its substrates. Here we analyzed the secretomes of Pseudomonas aeruginosa mutants altered in regulation of the Hcp Secretion Island-I-encoded type VI secretion system (H1-T6SS). We identified three substrates of this system, proteins Tse1-3 (type six exported 1-3), which are coregulated with the secretory apparatus and secreted under tight posttranslational control. The Tse2 protein was found to be the toxin component of a toxin-immunity system and to arrest the growth of prokaryotic and eukaryotic cells when expressed intracellularly. In contrast, secreted Tse2 had no effect on eukaryotic cells; however, it provided a major growth advantage for P. aeruginosa strains, relative to those lacking immunity, in a manner dependent on cell contact and the H1-T6SS. This demonstration that the T6SS targets a toxin to bacteria helps reconcile the structural and evolutionary relationship between the T6SS and the bacteriophage tail and spike.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Rachel D
authors.initials: RD
authors.lastname: Hood
authors.forename: Pragya
authors.initials: P
authors.lastname: Singh
authors.forename: Fosheng
authors.initials: F
authors.lastname: Hsu
authors.forename: Tüzün
authors.initials: T
authors.lastname: Güvener
authors.forename: Mike A
authors.initials: MA
authors.lastname: Carl
authors.forename: Rex R S
authors.initials: RR
authors.lastname: Trinidad
authors.forename: Julie M
authors.initials: JM
authors.lastname: Silverman
authors.forename: Brooks B
authors.initials: BB
authors.lastname: Ohlson
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Hicks
authors.forename: Rachael L
authors.initials: RL
authors.lastname: Plemel
authors.forename: Mo
authors.initials: M
authors.lastname: Li
authors.forename: Sandra
authors.initials: S
authors.lastname: Schwarz
authors.forename: Wenzhuo Y
authors.initials: WY
authors.lastname: Wang
authors.forename: Alexey J
authors.initials: AJ
authors.lastname: Merz
authors.forename: David R
authors.initials: DR
authors.lastname: Goodlett
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Mougous
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000633:toxicity; D000898:Antibiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism* / Q000633:toxicity; D001435:Bacteriophages / Q000235:genetics; D015169:Colony Count, Microbial; D019143:Evolution, Molecular; D023061:Gene Order; D044404:Genomic Islands; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D026901:Membrane Transport Proteins