Analysis of Vibrio cholerae genomes identifies new type VI secretion system gene clusters.

Background: Like many bacteria, Vibrio cholerae 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.

Horizontal Gene Transfer of Functional Type VI Killing Genes by Natural Transformation.

Horizontal gene transfer (HGT) can have profound effects on bacterial evolution by allowing individuals to rapidly acquire adaptive traits that shape their strategies for competition. One strategy for intermicrobial antagonism often used by is the genetically encoded contact-dependent type VI secretion system (T6SS), a weapon used to kill heteroclonal neighbors by direct injection of toxic effectors. Here, we experimentally demonstrate that can acquire new T6SS effector genes via horizontal transfer and utilize them to kill neighboring cells.

Whole-Genome Sequences of 26 Vibrio cholerae Isolates.

The human pathogen Vibrio cholerae employs several adaptive mechanisms for environmental persistence, including natural transformation and type VI secretion, creating a reservoir for the spread of disease. Here, we report whole-genome sequences of 26 diverse V. cholerae isolates, significantly increasing the sequence diversity of publicly available V.

CytR Is a Global Positive Regulator of Competence, Type VI Secretion, and Chitinases in Vibrio cholerae.

The facultative pathogen Vibrio cholerae transitions between its human host and aquatic reservoirs where it colonizes chitinous surfaces. Growth on chitin induces expression of chitin utilization genes, genes involved in DNA uptake by natural transformation, and a type VI secretion system that allows contact-dependent killing of neighboring bacteria. We have previously shown that the transcription factor CytR, thought to primarily regulate the pyrimidine nucleoside scavenging response, is required for natural competence in V.

Vibrio cholerae: Measuring Natural Transformation Frequency.

Many bacteria can become naturally competent to take up extracellular DNA across their outer and inner membranes by a dedicated competence apparatus. Whereas some studies show that the DNA delivered to the cytoplasm may be used for genome repair or for nutrition, it can also be recombined onto the chromosome by homologous recombination: a process called natural transformation. Along with conjugation and transduction, natural transformation represents a mechanism for horizontal transfer of genetic material, e.