Department of Biochemistry, Graduate School of Medicine, Konkuk University, Seoul 134-701, Korea.
J Biochem. 2010 Apr;147(4):511-22. doi: 10.1093/jb/mvp197. Epub 2009 Nov 23.
The gene encoding a catalase-peroxidase (KatG) was cloned from chromosomal DNA of a fast-growing Mycobacterium sp. strain JC1 DSM 3803. The nucleotide sequence of a 5.7 kb EcoRI fragment containing the katG and its flanking regions was determined. The fragment (5,706 bps) contained two complete open reading frames (ORFs) encoding putative ferric uptake regulator A (FurA) and KatG proteins. The cloned gene, katG, had an ORF of 2241 nt, encoding a protein with calculated molecular mass of 81,748 Da. The furA was located in the upstream of the katG with the same transcriptional direction and there was a 38 bp gap space between them. The deduced KatG and FurA protein sequences showed significant homologies to KatG2 and Fur2 of Mycobacterium smegmatis and clustered with other mycobacterial KatG and Fur-like proteins in phylogenetic trees, respectively. The recombinant KatG overproduced in Escherichia coli was nearly indistinguishable from the native JC1 catalase-peroxidase in enzymatic properties and also possessed the resistance to organic solvents, indicating that the cloned katG truly encodes the Mycobacterium sp. JC1 catalase-peroxidase. Difference spectroscopy revealed Mn(II) binding near the haem of the KatG. Transcript analysis of the furA-katG using RT-PCR suggests that the katG is independently transcribed from the furA.
从快速生长分枝杆菌 JC1DSM3803 的染色体 DNA 中克隆了编码过氧化氢酶过氧化物酶（KatG）的基因。确定了包含 katG 及其侧翼区的 5.7kbEcoRI 片段的核苷酸序列。该片段（5706 个碱基对）包含两个完整的开放阅读框（ORF），分别编码假定的铁摄取调节因子 A（FurA）和 KatG 蛋白。克隆的基因 katG 具有 2241 个核苷酸的 ORF，编码计算分子量为 81748Da 的蛋白质。FurA 位于 katG 的上游，具有相同的转录方向，它们之间有 38bp 的间隙空间。推断的 KatG 和 FurA 蛋白序列与分枝杆菌 smegmatis 的 KatG2 和 Fur2 具有显著的同源性，并分别在系统发育树中与其他分枝杆菌的 KatG 和 Fur 样蛋白聚类。在大肠杆菌中过表达的重组 KatG 在酶学特性上与天然 JC1 过氧化氢酶过氧化物酶几乎无法区分，并且还具有对有机溶剂的抗性，表明克隆的 katG 确实编码分枝杆菌 JC1 过氧化氢酶过氧化物酶。差异光谱显示 Mn(II)在 KatG 的血红素附近结合。使用 RT-PCR 对 furA-katG 的转录分析表明，katG 独立于 furA 转录。
