title: Characterization of the Aminotransferase ThdN from Thienodolin Biosynthesis in Streptomyces albogriseolus.
abstract: In Streptomyces albogriseolus the indolethiophen alkaloid thienodolin is derived from tryptophan. The first step in thienodolin biosynthesis is the regioselective chlorination of tryptophan in the 6-position of the indole ring. The second step is catalyzed by the aminotransferase ThdN. ThdN shows sequence homology (up to 69 % similarity) with known pyridoxal 5'-phosphate-dependent aminotransferases of the aspartate aminotransferase family from Gram-positive bacteria. thdN was heterologously expressed in Pseudomonas fluorescens, and the enzyme was purified by nickel-affinity chromatography. ThdN is a homodimeric enzyme with a mass of 90 600 kDa and catalyzes the conversion of l-tryptophan and a number of chlorinated and brominated l-tryptophans. The lowest KMvalues were found for 6-bromo- and 6-chlorotryptophan (40 and 66 μm, respectively). For l-tryptophan it was 454 μm, which explains why thienodolin is the major product and dechlorothienodolin is only a minor component. The turnover number (kcat) for 7-chlorotryptophan (128 min-1) was higher than that for the natural substrate 6-chlorotryptophan (88 min-1).
authors.affiliation: Professur für Allgemeine Biochemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062, Dresden, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Milbredt
authors.affiliation: Professur für Allgemeine Biochemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062, Dresden, Germany.
authors.forename: Eugenio P
authors.initials: EP
authors.lastname: Patallo
authors.affiliation: Professur für Allgemeine Biochemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062, Dresden, Germany. karl-heinz.vanpee@chemie.tu-dresden.de.
authors.forename: Karl-Heinz
authors.identifier: 0000-0001-8376-8821
authors.initials: KH
authors.lastname: van Pée
mesh_terms: D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D013302:Streptomyces / Q000201:enzymology / Q000378:metabolism*; D013876:Thiophenes / Q000737:chemistry / Q000378:metabolism*; D000637:Transaminases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007211:Indoles; D013876:Thiophenes; C000594502:thienodolin; D000637:Transaminases
keywords: aminotransferases; chlorotryptophan; enzyme catalysis; natural products; thienodolin