title: Overexpression, purification and characterization of SimL, an amide synthetase involved in simocyclinone biosynthesis.
abstract: Simocyclinone D8 is a potent inhibitor of bacterial gyrase, produced by Streptomyces antibioticus Tu 6040. It contains an aminocoumarin moiety, similar to that of novobiocin, which is linked by an amide bond to a structurally complex acyl moiety, consisting of an aromatic angucycline polyketide nucleus, the deoxysugar olivose and a tetraene dicarboxylic acid. We have now investigated the enzyme SimL, responsible for the formation of the amide bond of simocyclinone. The gene was cloned, expressed in S. lividans T7, and the protein was purified to near homogeneity, and characterized. The 60 kDa protein catalyzed both the ATP-dependent activation of the acyl component as well as its transfer to the amino group of the aminocoumarin ring, with no requirement for a 4'-phosphopantetheinyl cofactor. Besides its natural substrate, simocyclinone C4, SimL also accepted a range of cinnamic and benzoic acid derivatives and several other, structurally very diverse acids. These findings make SimL a possible tool for the creation of new aminocoumarin antibiotics.
authors.affiliation: Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Luft
authors.forename: Shu-Ming
authors.initials: SM
authors.lastname: Li
authors.forename: Holger
authors.initials: H
authors.lastname: Scheible
authors.forename: Bernd
authors.initials: B
authors.lastname: Kammerer
authors.forename: Lutz
authors.initials: L
authors.lastname: Heide
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019732:Amide Synthases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003067:Coenzymes / Q000494:pharmacology; D003374:Coumarins / Q000378:metabolism; D006027:Glycosides / Q000096:biosynthesis; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013303:Streptomyces antibioticus / Q000201:enzymology* / Q000235:genetics; D048170:Streptomyces lividans / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D003067:Coenzymes; D003374:Coumarins; D006027:Glycosides; D011994:Recombinant Proteins; C416814:simocyclinone D8; D000255:Adenosine Triphosphate; D019732:Amide Synthases