Cloning, expression, and biological function of a dTDP-deoxyglucose epimerase (gerF) gene from Streptomyces sp GERI-155

摘要

GERI-155 is a macrolide antibiotic containing two deoxyhexose molecules which has antimicrobial activities against Gram-positive bacteria. The deoxyhexose biosynthetic gene cluster of GERI-155 from Streptomyces sp. GERI-155 genome has now been isolated. Four orf were identified and a putative orf, supposed to code for the dTDP-deoxyglucose epimerase gene, was designated as gerF. gerF was expressed in E. coli using recombinant expression vector pHJ3. The recombinant protein expressed in a soluble form. The enzyme was purified by Ni-affinity column using imidazole buffer as eluents. The molecular mass of the expressed protein correlated with the predicted mass ( 36 000 Da) deduced from the cloned gene sequence data. The purified enzyme produced maltol from dTDP-4-keto-6-deoxyglucose and it was confirmed that the expressed proteinwas dTDP-deoxyglucose epimerase catalyzing epimerization of C-3 and C-5 or C-3 of dTDP-4-keto-6-deoxyglucose.