Evidence for arylamine N-acetyltransferase activity in Klebsiella pneumoniae
Chung-Sang Hui, Hsiu-Maan Kuo, Chun-Su Yu, Te-Mao Li
Department of Family Medicine, Jen-Ai Hospital, Tali, Taichung; Department of Parasitology, General Education Center, and 4School of Chinese Medicine, China Medical University, Taichung, Taiwan, ROC
Received: November 13, 2003 Revised: December 10, 2003 Accepted: January 13, 2004
Arylamine N-acetyltransferase (NAT) enzymes have been found in laboratory animals, humans, microorganisms (fungi, bacteria and parasites), and in plants. But the characteristics of NAT from Klebsiella pneumoniae are not clear. NAT activities with p-aminobenzoic acid (PABA) and 2-aminofluorene (AF) as substrates were examined in the cytosol of K. pneumoniae. NAT activity (N-acetylation of substrates) was determined using an acetyl coenzyme A recycling assay and high performance liquid chromatography for determining the amounts of acetylated or non-acetylated PABA or AF. NAT activities from a number of K. pneumoniae isolates were found to be 0.72 ± 0.08 nmol/min/mg protein for AF, and 0.49 ± 0.04 nmol/min/mg protein for PABA. The kinetic parameters of apparent Michaelis constant (Km) and maximum velocity (Vmax) obtained were 2.92 ± 0.48 mM and 7.89 ± 0.82 nmol/min/mg protein, respectively, for AF and 2.42 ± 0.28 mM and 9.87 ± 0.64 nmol/min/mg protein, respectively, for PABA. The optimal pH value for the NAT activity was 7.0 for AF and PABA. The optimal temperature for NAT activity was 37ºC for both substrates. The NAT activity was inhibited by 50% with 0.25 mM iodoacetamide, and by more than 90% at 1.0 mM. Among a series of divalent cations and salts, Cu2+ and Zn2+ were the most potent inhibitors of NAT activity.
N-acetyltransferase, 4-aminobenzoic acid, 2-aminofluorene, Klebsiella pneumoniae, mRNA
J Microbiol Immunol Infect 2004;37:208-215.