The Alternative Sigma Factor RpoE2 Is Involved in the Stress Response to Hypochlorite and Survival of .

Extracytoplasmic function (ECF) sigma factors underpin the ability of bacteria to adapt to changing environmental conditions, a process that is particularly relevant in human pathogens that inhabit niches where human immune cells contribute to high levels of extracellular stress. Here, we have characterized the previously unstudied RpoE2 ECF sigma factor from the human respiratory pathogen (Hi) and its role in hypochlorite-induced stress. Exposure of to oxidative stress (HOCl, HO) increased gene expression, and the activity of RpoE2 was controlled by a cytoplasmic 67-aa anti-sigma factor, HrsE.

Peptide Methionine Sulfoxide Reductase from Is Required for Protection against HOCl and Affects the Host Response to Infection.

Peptide methionine sulfoxide reductases (Msrs) are enzymes that repair ROS-damage to sulfur-containing amino acids such as methionine, ensuring functional integrity of cellular proteins. Here we have shown that unlike the majority of pro- and eukaryotic Msrs, the peptide methionine sulfoxide reductase (MsrAB) from the human pathobiont (Hi) is required for the repair of hypochlorite damage to cell envelope proteins, but more importantly, we were able to demonstrate that MsrAB plays a role in modulating the host immune response to Hi infection. Loss of MsrAB resulted in >1000-fold increase in sensitivity of Hi to HOCl-mediated killing, and also reduced biofilm formation and in-biofilm survival.