PT  - JOURNAL ARTICLE
AU  - Cristian V. Crisan
AU  - Aroon T. Chande
AU  - Kenneth Williams
AU  - Vishnu Raghuram
AU  - Lavanya Rishishwar
AU  - Gabi Steinbach
AU  - Peter Yunker
AU  - I. King Jordan
AU  - Brian K. Hammer
TI  - Analysis of <em>Vibrio cholerae</em> genomes using a novel bioinformatic tool identifies new, active Type VI Secretion System gene clusters
AID  - 10.1101/526723
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 526723
4099  - http://biorxiv.org/content/early/2019/01/26/526723.short
4100  - http://biorxiv.org/content/early/2019/01/26/526723.full
AB  - Background Like many bacteria, Vibrio cholerae, which causes fatal cholera, deploys a harpoon-like Type VI Secretion System (T6SS) to compete against other microbes in environmental and host settings. The T6SS punctures adjacent cells and delivers toxic effector proteins that are harmless to bacteria carrying cognate immunity factors. Only four effector/immunity pairs encoded on one large and three auxiliary gene clusters have been characterized from largely clonal, patient-derived strains of V. cholerae.Results We sequenced two dozen V. cholerae strain genomes from diverse sources and developed a novel and adaptable bioinformatic tool based on Hidden Markov Models. We identified two new T6SS auxiliary gene clusters; one, Aux 5, is described here. Four Aux 5 loci are present in the host strain, each with an atypical effector/immunity gene organization. Structural prediction of the putative effector indicated it is a lipase, which we name TleV1 (Type VI lipase effector Vibrio, TleV1). Ectopic TleV1 expression induced toxicity in E. coli, which was rescued by co-expression of the TleV1 immunity factor. A clinical V. cholerae reference strain expressing the Aux 5 cluster used TleV1 to lyse its parental strain upon contact via its T6SS but was unable to kill parental cells expressing TleV1’s immunity factor.Conclusion We developed a novel bioinformatic method and identified new T6SS gene clusters in V. cholerae. We also showed the TleV1 toxin is delivered in a T6SS-manner by V. cholerae and can lyse other bacterial cells. Our web-based tool may be modified to identify additional novel T6SS genomic loci in diverse bacterial species.