title: Characterization of a regiospecific epivancosaminyl transferase GtfA and enzymatic reconstitution of the antibiotic chloroeremomycin.
abstract: Chloroeremomycin, a vancomycin family glycopeptide antibiotic has three sugars, one D-glucose and two L-4-epi-vancosamines, attached to the crosslinked heptapeptide backbone by three glycosyltransferases, GtfA, -B, and -C. Prior efforts have revealed that GtfB and -C in tandem build an epivancosaminyl-1,2-glucosyldisaccharide chain on residue 4 of the aglycone; however, the characterization of GtfA and glycosylation sequence of chloroeremomycin have been lacking. Here, we report the expression and purification of GtfA, as well as synthesis of its sugar donor, 2'-deoxy-thymidine 5'-diphosphate (dTDP)-beta-L-4-epi-vancosamine. GtfA transfers 4-epi-vancosamine from the chemically synthesized dTDP-4-epi-vancosamine to the beta-OH-Tyr6 residue of the aglycone, preferentially after GtfB action, to generate chloroorienticin B. With the preferred kinetic order of GtfB, then GtfA, then GtfC established, we have succeeded in reconstitution of chloroeremomycin from the heptapeptide aglycone by the sequential actions of the three enzymes.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.forename: Markus
authors.initials: M
authors.lastname: Oberthür
authors.forename: Catherine
authors.initials: C
authors.lastname: Leimkuhler
authors.forename: Junhua
authors.initials: J
authors.lastname: Tao
authors.forename: Daniel
authors.initials: D
authors.lastname: Kahne
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Walsh
mesh_terms: D000192:Actinomycetales / Q000201:enzymology*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006031:Glycosylation; D007700:Kinetics; D013379:Substrate Specificity; D000637:Transaminases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D014640:Vancomycin / Q000031:analogs & derivatives* / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; C112142:chloroeremomycin; D014640:Vancomycin; C477600:TDP-epi-vancosaminyltransferase; D000637:Transaminases