BagZH Encoding Tyrosinase-like Copper Enzyme Participates In Biosynthesis Pathway Of Bagremycin

Streptomyces sp.Tü 4128 was isolated from a soil collected in Java,Indonesia.The novel secondary metabolites,bagremycin A and B,were detected in the culture filtrate of Streptomyces sp.Tü 4128,which have potential value in finding and modifying new antibiotics.Bagremycin A is combinated with p-coumalic acid and 3,4-AHBA in vivo,as presumed,and bagremycin B is the derivative of bagremycin A via acetylation.To investigate the biosynthesis pathway of bagremycins and gene cluster,bagZ,bagH,bagZH and bagK were deleted,which were confirmed in both DNA and RNA levels.According to analysis of HPLC,production of bagremycin was reduced when bagZ and/or bagH were deleted,suggesting bagZH has positive correlation with bagremycin;while production of bagremycin was increased while bagK was deleted,suggesting bagK has negative correlation with bagremycin.Complement of bagZ and bagH didn't recover the accumulation of bagremycins,while the overexpression of bagZ and bagH made the accumulation of bagremycins improved.It is suggested that bagZ and bagH are polycistron on the chromosome,and the destructive structure is not permitted.BagZ assists in protein folding,and transfers Cu2+to BagH,activating the enzyme activity.BagH oxidates o-aminophenol in vitro,with amino group turning into nitroso-group.BagH is predicted to protect the amino group from destroying when 3,4-AHBA is condensating with styrene,and the nitroso-group will be reducted by reductase in vivo,generating bagremycin A.In addition,BagB and BagC are responsible for the synthesis of 3,4-AHBA in the biosynthesis pathway of bagremycins,which was demonstrated by experiments.