title: Biochemical and structural insights of the early glycosylation steps in calicheamicin biosynthesis.
abstract: The enediyne antibiotic calicheamicin (CLM) gamma(1)(I) is a prominent antitumor agent that is targeted to DNA by a novel aryltetrasaccharide comprised of an aromatic unit and four unusual carbohydrates. Herein we report the heterologous expression and the biochemical characterization of the two "internal" glycosyltransferases CalG3 and CalG2 and the structural elucidation of an enediyne glycosyltransferase (CalG3). In conjunction with the previous characterization of the "external" CLM GTs CalG1 and CalG4, this study completes the functional assignment of all four CLM GTs, extends the utility of enediyne GT-catalyzed reaction reversibility, and presents conclusive evidence of a sequential glycosylation pathway in CLM biosynthesis. This work also reveals the common GT-B structural fold can now be extended to include enediyne GTs.
authors: Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 Xingang West Road, Guangzhou, China.
authors: Changsheng
authors: C
authors: Zhang
authors: Eduard
authors: E
authors: Bitto
authors: Randal D
authors: RD
authors: Goff
authors: Shanteri
authors: S
authors: Singh
authors: Craig A
authors: CA
authors: Bingman
authors: Byron R
authors: BR
authors: Griffith
authors: Christoph
authors: C
authors: Albermann
authors: George N
authors: GN
authors: Phillips
authors: Jon S
authors: JS
authors: Thorson
mesh_terms: D000617:Aminoglycosides / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D019281:Dimerization; D053281:Enediynes / Q000378:metabolism; D006031:Glycosylation; D016695:Glycosyltransferases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D008847:Micromonospora / Q000201:enzymology; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary
chemical_list: D000617:Aminoglycosides; D053281:Enediynes; D009711:Nucleotides; C422086:calicheamicinone; C055955:calicheamicin gamma(1)I; D016695:Glycosyltransferases