A type VI secretion system of Pseudomonas aeruginosa targets a toxin to bacteria.
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.
Hood
Rachel D
RD
Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
Singh
Pragya
P
Hsu
Fosheng
F
Güvener
Tüzün
T
Carl
Mike A
MA
Trinidad
Rex R S
RR
Silverman
Julie M
JM
Ohlson
Brooks B
BB
Hicks
Kevin G
KG
Plemel
Rachael L
RL
Li
Mo
M
Schwarz
Sandra
S
Wang
Wenzhuo Y
WY
Merz
Alexey J
AJ
Goodlett
David R
DR
Mougous
Joseph D
JD
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*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D026901:Membrane Transport Proteins