Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. Plays a role in the regulation of many virulence factors, motility, quorum sensing, mucoidy, a general mechanism for maintaining lytic phage in populations of bacteria, and biofilm formation. Positively controls the T6 secretion system by directly binding to the promoter regions of hcpA and hcpB genes, leading to their expression. Thereby, allows to colonize several hosts efficiently including mammals, insects, nematodes and plants 