Streptomyces Hygroscopicus 17997 Geldanamycin Organisms Biosynthetic Gene Cluster In The Function Of Two Regulatory Genes

Streptomyces hygroscopicus 17997 was isolated from Chinese soil and it can produce Geldanamycin (GDM). GDM, belonging to the benzenenoid ansamycin, possesses antitumor and antiprotozoon activity and recently, was discovered that it shows antivirus bioactivity. Extensive research have vertified that GDM can bind specifically to the ATP/ADP domain of heat shock protein 90 (Hsp90), thus down-regulate target proteins including tyrosine kinases, steroid receptors, transcription factors et al. As a specific inhibitor of Hsp90, GDM became a potential promising antitumor and antivirus medicine.During previous studies, some of the geldanamycin biosynthetic genes were obtained from Streptomyces hygroscopicus 17997, including two possible transcriptional regulation genes gdmRI and gdmRII. In this study, for the purpose of investigating functions of the two regulation genes, the plasmid containing gdmRI or gdmRII disrupted gene was constructed, repectively. Then by conjugal transfer, the gdmRI and gdmRII disrupted gene was separately introduced into Streptomyces hygroscopicus 17997. By way of cultivation and resistance selecting, two mutant strains were acquired, in which gdmRI and gdmRII were blocked, respectively. Analysing the products of two mutants by TLC and HPLC, some conclusions were made: (1) Almost no GDM production was detected when the two genes were disrupted, respectively; (2) After introducing the plasmid carrying complete gdmRI gene into the corresponding mutant strain, the production of GDM was recovered to 50% of that of wild type strain. The above results indicated that the two transcriptional regulatory genes, gdmRI and gdmRII, played the positive regulatory role in GDM biosynthesis.