Roles of Staphylococcus aureus Mnh1 and Mnh2 Antiporters in Salt Tolerance, Alkali Tolerance, and Pathogenesis. Journal Article

Authors: Vaish, M; Price-Whelan, A; Reyes-Robles, T; Liu, J; Jereen, A; Christie, S; Alonzo, F; Benson, MA; Torres, VJ; Krulwich, TA
Article Title: Roles of Staphylococcus aureus Mnh1 and Mnh2 Antiporters in Salt Tolerance, Alkali Tolerance, and Pathogenesis.
Abstract: has three types of cation/proton antiporters. The type 3 family includes two ultisubunit a/ (Mnh) antiporters, Mnh1 and Mnh2. These antiporters are clusters of seven hydrophobic membrane-bound protein subunits. Mnh antiporters play important roles in maintaining cytoplasmic pH in prokaryotes, enabling their survival under extreme environmental stress. In this study, we investigated the physiological roles and catalytic properties of Mnh1 and Mnh2 in Both Mnh1 and Mnh2 were cloned separately into a pGEM3Z+ vector in the antiporter-deficient KNabc strain. The catalytic properties of the antiporters were measured in everted (inside out) vesicles. The Mnh1 antiporter exhibited a significant exchange of Na/H cations at pH 7.5. Mnh2 showed a significant exchange of both Na/H and K/H cations, especially at pH 8.5. Under elevated salt conditions, deletion of the gene resulted in a significant reduction in the growth rate of in the range of pH 7.5 to 9. Deletion of had similar effects but mainly in the range of pH 8.5 to 9.5. Double deletion of and led to a severe reduction in the growth rate mainly at pH values above 8.5. The effects of functional losses of both antiporters in were also assessed via their support of virulence in a mouse infection model. Deletion of the gene led to a major loss of virulence in mice, while deletion of led to no change in virulence. This study focuses on the catalytic properties and physiological roles of Mnh1 and Mnh2 cation/proton antiporters in and their contributions under different stress conditions. The Mnh1 antiporter was found to have catalytic activity for Na/H antiport, and it plays a significant role in maintaining halotolerance at pH 7.5 while the Mnh2 antiporter has catalytic antiporter activities for Na/H and K/H that have roles in both osmotolerance and halotolerance in Study of with a single deletion of either or was assessed in an infection model of mice. The result shows that , but not , plays a major role in virulence.
Journal Title: Journal of Bacteriology
ISSN: 1098-5530; 0021-9193
Publisher: Unknown  
Date Published: 2018