Trend M A, Jorgensen M A, Hazell S L, Mendz G L
School of Biochemistry and Molecular Genetics, The University of New South Wales, NSW 2052, Sydney, Australia.
Int J Biochem Cell Biol. 2001 Feb;33(2):143-53. doi: 10.1016/s1357-2725(00)00085-6.
Helicobacter pylori is a contributing factor to the development of gastric and duodenal ulcers and some gastric cancers. Some therapeutic regimes comprise of a number of components, one of which is the antimicrobial metronidazole. A problem with these therapies is the increasing prevalence of metronidazole-resistant (MtrR) H. pylori strains. Several resistance mechanisms have been proposed, and this study addresses the 'scavenging of oxygen' hypothesis. Spectrophotometric assays of cytosolic fractions indicated that metronidazole-sensitive (MtrS) H. pylori isolates had 2.6-fold greater nicotinamide adenine dinucleotide (NADH) oxidase activity, 34-fold greater NADH nitroreductase activity, and eightfold greater nicotinamide adenine dinucleotide phosphate (NADPH) nitroreductase activity than cytosolic fractions from matched MtrR strains. Electrophoresis of cytosolic fractions in non-denaturing gels showed up to 10 protein bands when stained with Coomassie blue. Activity staining of non-denaturing, non-reducing polyacrylamide gels detected NAD(P)H oxidase, disulphide reductase, tetrazolium reductase and nitroreductase activities in the protein bands. Oxidase and reductase activities observed in a band from MtrS strains were absent in the corresponding band from MtrR strains. This band comprised at least 13 proteins, and the major constituent was identified as an alkyl hydroperoxide reductase AhpC subunit. The absence of oxidase and reductase activities in the band from MtrR strains indicated a correlation between the activity of the proteins in this band and the metronidazole-sensitive phenotype.
幽门螺杆菌是导致胃溃疡、十二指肠溃疡以及某些胃癌的一个因素。一些治疗方案包含多种成分，其中之一是抗菌药物甲硝唑。这些疗法存在的一个问题是对甲硝唑耐药的幽门螺杆菌菌株的患病率不断上升。已经提出了几种耐药机制，本研究探讨“清除氧气”假说。对胞质组分的分光光度测定表明，与匹配的甲硝唑耐药（MtrR）菌株的胞质组分相比，甲硝唑敏感（MtrS）的幽门螺杆菌分离株的烟酰胺腺嘌呤二核苷酸（NADH）氧化酶活性高2.6倍，NADH硝基还原酶活性高34倍，烟酰胺腺嘌呤二核苷酸磷酸（NADPH）硝基还原酶活性高8倍。用考马斯亮蓝染色时，非变性凝胶中胞质组分的电泳显示多达10条蛋白带。非变性、非还原聚丙烯酰胺凝胶的活性染色检测到蛋白带中的NAD(P)H氧化酶、二硫键还原酶、四氮唑还原酶和硝基还原酶活性。在MtrS菌株的一条带中观察到的氧化酶和还原酶活性在MtrR菌株的相应带中不存在。这条带至少包含13种蛋白质，主要成分被鉴定为烷基过氧化氢还原酶AhpC亚基。MtrR菌株带中氧化酶和还原酶活性的缺失表明该带中蛋白质的活性与甲硝唑敏感表型之间存在相关性。
