Multicellular Bacteria Deploy the Type VI Secretion System to Preemptively Strike Neighboring Cells

• DOI: 10.1371/journal.ppat.1003608
• Publication Date: 2013-09-05T21:24:47Z
• Authors: Christopher J. Al...; Stephanie D. Himpsl; Shannon R. Pickens; Jonathon R. Lindner; Jonathan S. Zora; Jessa E. Miller; Peter D. Arno; Samuel W. Straight; Harry L. T. Mobley
• Keywords: Multicellular organism; Transposon mutagenesis; Swarming (honey bee); Swarming motility

The Type VI Secretion System (T6SS) functions in bacteria as a contractile nanomachine that punctures and delivers lethal effectors to target cell. Virtually nothing is known about the lifestyle or physiology dictates when normally produce their T6SS, which prevents clear understanding of how benefit from its action natural habitat. Proteus mirabilis undergoes characteristic developmental process coordinate multicellular swarming behavior will discriminate itself another isolate during swarming, resulting visible boundary termed Dienes line. Using transposon mutagenesis, we discovered this recognition phenomenon requires T6SS. All mutants identified genetic screen had insertions within single 33.5-kb region encodes T6SS cognate Hcp-VrgG-linked effectors. primary effector operons were characterized by killing assays, construction additional mutants, complementation, examining activity type secretion system real-time using live-cell microscopy on opposing swarms. We show T6SS-dependent occurs dominant strain infiltrates deeply beyond two model, found social bacteria, underlying killing, immunity all require cell-cell contact, can be assigned specific genes, are dependent ability survive attack equates "recognition". In contrast current model being an offensive defensive weapon our findings support preemptive mechanism entire population indiscriminately uses for contact-dependent delivery cooperative mode growth.