Identification of the enzyme responsible for N-acetylation of norfloxacin by Microbacterium sp. Strain 4N2-2.

ABSTRACT: Microbacterium sp. 4N2-2, isolated from a wastewater treatment plant, converts the antibacterial fluoroquinolone norfloxacin to N-acetylnorfloxacin and three other metabolites. Because N-acetylation results in loss of antibacterial activity, identification of the enzyme responsible is important for understanding fluoroquinolone resistance. The enzyme was identified as glutamine synthetase (GS); N-acetylnorfloxacin was produced only under conditions associated with GS expression. The GS gene (glnA) was cloned, and the protein (53 kDa) was heterologously expressed and isolated. Optimal conditions and biochemical properties (K(m) and V(max)) of purified GS were characterized; the purified enzyme was inhibited by Mn(2+), Mg(2+), ATP, and ADP. The contribution of GS to norfloxacin resistance wa

SUBMITTER: Kim DW 

PROVIDER: S-EPMC3536110 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature