期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 277, 期 4, 页码 2886-2896出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M109377200
关键词
-
资金
- NCI NIH HHS [P30-CA-14236] Funding Source: Medline
- NIGMS NIH HHS [GM-51310] Funding Source: Medline
Addition of the 4-amino-4-deoxy-L-arabinose (L-Ara4N) moiety to the phosphate groups of lipid A is implicated in bacterial resistance to polymyxin and cationic antimicrobial peptides of the innate immune system. The sequences of the products of the Salmonella typhimurium pmrE andpmrF loci, both of which are required for polymyxin resistance, recently led us to propose a pathway for L-Ara4N biosynthesis from UDP-glucuronic acid (Zhou, Z., Lin, S., Cotter, R. J., and Raetz, C. R. H. (1999) J. Biol. Chem. 274, 18503-18514). We now report that extracts of a polymyxin-resistant mutant of Escherichia coli catalyze the C-4 oxidation and C-6 decarboxylation of [alpha-P-32]UDP-glucuronic acid, followed by transamination to generate [alpha-P-32]UDP-L-Ara4N, when NAD and glutamate are added as co-substrates. In addition, the [alpha-(32)p]UDP-L-Ara4N is formylated when N-10-formyltetrahydrofolate is included. These activities are consistent with the proposed functions of two of the gene products (PmrI and PmrH) of the pmrF operon. PmrI (renamed ArnA) was overexpressed using a T7 construct, and shown by itself to catalyze the unprecedented oxidative decarboxylation of UDP-glucuronic acid to form uridine 5'-(beta-L-threo-pentapyranosyl-4-ulose diphosphate). A 6-mg sample of the latter was purified, and its structure was validated by NMR studies as the hydrate of the 4 ketone. ArnA resembles UDP-galactose epimerase, dTDP-glucose-4,6-dehydratase, and UDP-xylose synthase in oxidizing the C-4 position of its substrate, but differs in that it releases the NADH product.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据