Tornus D, Floss H G
Department of Chemistry, University of Washington, Seattle 98195-1700, USA.
J Antibiot (Tokyo). 2001 Jan;54(1):91-101. doi: 10.7164/antibiotics.54.91.
Four genes, ORF 22 approximately 25, from the granaticin biosynthetic gene cluster of Streptomyces violaceoruber Tü22 were analyzed for their involvement in the biosynthesis of the two deoxysugar moieties of the granaticins. Each gene was individually inactivated on a cosmid carrying the entire gra gene cluster and the mutant cosmids were transformed into S. coelicolor CH999. Analysis of the pattern of pigment production by the transformants revealed that each of the four ORFs is required for the formation/attachment of the L-rhodinose moiety of granaticin B, but not that of the D-olivose moiety of granaticin. Based on these results and sequence homologies a pathway of dTDP-L-rhodinose formation is proposed which implicates ORF23, and possibly also ORF 24, in the 3-deoxygenation reaction, ORF 25 in the epimerization and ORF 22 in the final 4-ketoreduction.
对来自紫红红链霉菌Tü22的granaticin生物合成基因簇中的4个基因（ORF 22至约25）进行了分析，以确定它们是否参与granaticins两个脱氧糖部分的生物合成。每个基因分别在携带完整gra基因簇的黏粒上失活，然后将突变的黏粒转化到天蓝色链霉菌CH999中。对转化体色素产生模式的分析表明，这4个ORF中的每一个都是granaticin B的L-鼠李糖部分形成/连接所必需的，但不是granaticin的D-橄榄糖部分形成所必需的。基于这些结果和序列同源性，提出了dTDP-L-鼠李糖形成的途径，其中ORF23可能还有ORF 24参与3-脱氧反应，ORF 25参与差向异构化，ORF 22参与最后的4-酮还原反应。
