期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：5
页码：2316-2321
DOI：10.1073/pnas.0337708100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Ring A (3-dimethylallyl-4-hydroxybenzoic acid) is a structural moiety of the aminocoumarin antibiotics novobiocin and clorobiocin. In the present study, the prenyltransferase involved in the biosynthesis of this moiety was identified from the clorobiocin producer (Streptomyces roseochromogenes), overexpressed, and purified. It is a soluble, monomeric 35-kDa protein, encoded by the structural gene cloQ. 4-Hydroxyphenylpyruvate and dimethylallyl diphosphate were identified as the substrates of this enzyme, with Km values determined as 25 and 35 {micro}M, respectively. A gene inactivation experiment confirmed that cloQ is essential for ring A biosynthesis. Database searches did not reveal any similarity of CloQ to known prenyltransferases, and the enzyme did not contain the typical prenyl diphosphate binding site (N/D)DXXD. In contrast to most of the known prenyltransferases, the enzymatic activity was not dependent on the presence of magnesium, and in contrast to the membrane-bound polyprenyltransferases involved in ubiquinone biosynthesis, CloQ did not accept 4-hydroxybenzoic acid as substrate. CloQ and the similar NovQ from the novobiocin producer seem to belong to a new class of prenyltransferases.
