title: Characterization of Enzymes Catalyzing Transformations of Cysteine S-Conjugated Intermediates in the Lincosamide Biosynthetic Pathway.
abstract: Lincosamides such as lincomycin A, celesticetin, and Bu-2545, constitute an important group of antibiotics. These natural products are characterized by a thiooctose linked to a l-proline residue, but they differ with regards to modifications of the thioacetal moiety, the pyrrolidine ring, and the octose core. Here we report that the pyridoxal 5'-phosphate-dependent enzyme CcbF (celesticetin biosynthetic pathway) is a decarboxylating deaminase that converts a cysteine S-conjugated intermediate into an aldehyde. In contrast, the homologous enzyme LmbF (lincomycin biosynthetic pathway) catalyzes C-S bond cleavage of the same intermediate to afford a thioglycoside. We show that Ccb4 and LmbG (downstream methyltransferases) convert the aldehyde and thiol intermediates into a variety of methylated lincosamide compounds including Bu-2545. The substrates used in these studies are the β-anomers of the natural substrates. The findings not only provide insight into how the biosynthetic pathway of lincosamide antibiotics can bifurcate to generate different lincosamides, but also reveal the promiscuity of the enzymes involved.
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Department of Chemistry, University of Texas at Austin, 1 University Station A1935, Austin, TX, 78712, USA.
authors.forename: Richiro
authors.initials: R
authors.lastname: Ushimaru
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Department of Chemistry, University of Texas at Austin, 1 University Station A1935, Austin, TX, 78712, USA.
authors.forename: Chia-I
authors.initials: CI
authors.lastname: Lin
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Department of Chemistry, University of Texas at Austin, 1 University Station A1935, Austin, TX, 78712, USA.
authors.forename: Eita
authors.initials: E
authors.lastname: Sasaki
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Department of Chemistry, University of Texas at Austin, 1 University Station A1935, Austin, TX, 78712, USA. h.w.liu@mail.utexas.edu.
authors.forename: Hung-Wen
authors.initials: HW
authors.lastname: Liu
mesh_terms: D055162:Biocatalysis; D053898:Biosynthetic Pathways; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism*; D055231:Lincosamides / Q000096:biosynthesis* / Q000737:chemistry; D008780:Methyltransferases / Q000378:metabolism*; D015394:Molecular Structure; D013302:Streptomyces / Q000201:enzymology
chemical_list: D055231:Lincosamides; D008780:Methyltransferases; D003545:Cysteine
keywords: biosynthesis; catalytic mechanisms; enzymes; lincosamides; pyridoxal 5′-phosphate