Expanding the manganese regulon in Escherichia coli: a new small protein, mntS and efflux pump, mntP

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	NICHD	MOLBIO-13

* FARE Award Winner

Authors

• L Waters
• M Sandoval
• G Storz

Abstract

Manganese is an essential micronutrient for organisms from bacteria to humans, serving as an enzyme cofactor and protecting cells against oxidative stress. Yet manganese is toxic in excess. Therefore, cells must carefully regulate manganese homeostasis and intracellular trafficking. We have discovered a novel manganese homeostasis gene in E. coli, mntS, which encodes a small, 42-amino acid protein and is repressed by high manganese levels. Overexpression of MntS causes sensitivity to manganese, while deletion of mntS perturbs the regulated expression of the MntH manganese transporter. As initial experiments indicate that mntS can bind manganese, we propose that mntS may function as a manganese chaperone to accurately deliver manganese to specific enzymes under normal and stress conditions. We also identified mntP (formerly yebN) as the first gene positively regulated by manganese in Enterobacteria. Deletion of mntP leads to profound manganese sensitivity and to elevated intracellular manganese levels. Given its homology to the LysE family of exporters, we propose that mntP represents a novel type of manganese efflux pump, the first known in gram-negative bacteria. Future work is aimed at characterizing a riboswitch element upstream of mntP that may serve to integrate diverse environmental signals into the regulation of intracellular manganese concentration.

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