ZmaR, a novel and widespread antibiotic resistance determinant that acetylates zwittermicin A

ZmaR is a resistance determinant of unusual abundance in the environment an d confers on gram-positive and gram-negative bacteria resistance to zwitter micin A, a novel broad-spectrum antibiotic produced by species of Bacillus. The ZmaR protein has no sequence similarity to proteins of known function; thus, the purpose of the present study was to determine the function of Zm aR in vitro. Cell extracts of E. coli containing zmaR inactivated zwittermi cin A by covalent modification. Chemical analysis of inactivated zwittermic in A by H-1 NMR, C-13 NMR, and high- and low-resolution mass spectrometry d emonstrated that the inactivated zwittermicin A was acetylated. Purified Zm aR protein inactivated zwittermicin A, and biochemical assays for acetyltra nsferase activity with [C-14]acetyl coenzyme A demonstrated that ZmaR catal yzes the acetylation of zwittermicin A with acetyl coenzyme A as a donor gr oup, suggesting that ZmaR may constitute a new class of acetyltransferases. Our results allow us to assign a biochemical function to a resistance prot ein that has no sequence similarity to proteins of known function, contribu ting fundamental knowledge to the fields of antibiotic resistance and prote in function.