| The Gram-negative bacterium Vibrio cholerae is the etiological agent of cholera, a disease responsible for more than 100,000 deaths annually. Many medically important proteobacteria, including V. cholerae, have been shown to carry at least one copy of the gene cluster to encode the bacterial type VI secretion system (T6SS) that contributes to the virulent behaviour of the bacteria. Despite increasing research efforts, T6SS regulatory mechanisms remain elusive. This thesis reports a molecular study of a putative global regulator VasH. The study attempted to determine if VasH functions as a sigma-54 activator protein that controls expression of the V. cholerae T6SS. Through bioinformatics and mutagenesis analyses, the roles of VasH in various endemic and pandemic V. cholerae strains were demonstrated, providing insight into how T6SS is regulated and utilized during the V. cholerae life cycle. |
