title: The thioesterase Bhp is involved in the formation of beta-hydroxytyrosine during balhimycin biosynthesis in Amycolatopsis balhimycina.
abstract: The putative hydrolase gene bhp from the balhimycin biosynthetic gene cluster has been cloned and overexpressed in Escherichia coli. The corresponding enzyme Bhp was purified to homogeneity by nickel-chelating chromatography and characterized. Although Bhp has sequence similarities to hydrolases with "haloperoxidase"/perhydrolase activity, it did not show any enzymatic activity with standard "haloperoxidase"/perhydrolase substrates (e.g., monochlorodimedone and phenol red), nonspecific esterase substrates (such as p-nitrophenyl acetate, p-nitrophenyl phosphate and S-thiophenyl acetate) or the model lactonase substrate dihydrocoumarin. However, Bhp could be shown to catalyse the hydrolysis of S-beta-hydroxytyrosyl-N-acetyl cysteamine thioester (beta-OH-Tyr-SNAC) with 15 times the efficiency of S-L-tyrosyl-N-acetyl cysteamine thioester (L-Tyr-SNAC). This is in agreement with the suggestion that Bhp is involved in balhimycin biosynthesis, during which it was supposed to catalyse the hydrolysis of beta-OH-Tyr-S-PCP (PCP=peptidyl carrier protein) to free beta-hydroxytyrosine (beta-OH-Tyr) and strongly suggests that Bhp is a thioesterase with high substrate specificity for PCP-bound beta-OH-Tyr and not a "haloperoxidase"/perhydrolase or nonspecific esterase.
authors.affiliation: Biochemistry, TU Dresden, 01062 Dresden, Germany.
authors.forename: Sri
authors.initials: S
authors.lastname: Mulyani
authors.forename: Ellen
authors.initials: E
authors.lastname: Egel
authors.forename: Claudia
authors.initials: C
authors.lastname: Kittel
authors.forename: Suada
authors.initials: S
authors.lastname: Turkanovic
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wohlleben
authors.forename: Roderich D
authors.initials: RD
authors.lastname: Süssmuth
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: van Pée
mesh_terms: D000192:Actinomycetales / Q000201:enzymology* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D055162:Biocatalysis; D004295:Dihydroxyphenylalanine / Q000378:metabolism*; D005810:Multigene Family; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism*; D014640:Vancomycin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; C087127:balhimycin; D004295:Dihydroxyphenylalanine; D014640:Vancomycin; D013869:Thiolester Hydrolases