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The Thioesterase Bhp is Involved in the Formation of β‐Hydroxytyrosine during Balhimycin Biosynthesis in Amycolatopsis balhimycina
Authors:Sri Mulyani Dr  Ellen Egel  Claudia Kittel Dr  Suada Turkanovic  Wolfgang Wohlleben Prof  Roderich D Süssmuth Prof  Karl‐Heinz van Pée Prof
Affiliation:1. Biochemistry, TU Dresden, 01062 Dresden (Germany), Fax: (+49)?351‐463‐35506;2. Prodi P. Kimia, FKIP, Universitas Sebelas Maret, Jl. Ir. Sutami 36 A, Surakarta 57126 (Indonesia);3. Lehrstuhl für Mikrobiologie/Biotechnologie, Eberhard‐Karls‐Universit?t Tübingen, Auf der Morgenstelle 28, 72076 Tübingen (Germany);4. Institut für Chemie/FG Organische Chemie, Technische Universit?t Berlin, TC Geb?ude TC2, Strasse des 17. Juni 124, 10623 Berlin (Germany)
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‐β‐hydroxytyrosyl‐N‐acetyl cysteamine thioester (β‐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 β‐OH‐Tyr‐S‐PCP (PCP=peptidyl carrier protein) to free β‐hydroxytyrosine (β‐OH‐Tyr) and strongly suggests that Bhp is a thioesterase with high substrate specificity for PCP‐bound β‐OH‐Tyr and not a “haloperoxidase”/perhydrolase or nonspecific esterase.
Keywords:antibiotics  balhimycin  beta‐hydroxytyrosine  glycopeptides  thioesterases  vancomycin
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