 At least one member (YebN of "E. coli", TC# 2.A.107.1.1) has been shown to function as a putative manganese efflux pump.Manganese sensitivity and intracellular manganese levels significantly increased in bacteria when the "mntP" (formerly "yebN") gene, which encodes the MntP efflux pump, was deleted.While manganese is a highly important trace nutrient for organisms from bacteria to humans, acting as an important element in the defense against oxidative stress and as an enzyme cofactor, it becomes toxic when present in excess.