title: Crystal structure of carbapenem synthase (CarC).
abstract: The proposed biosynthetic pathway to the carbapenem antibiotics proceeds via epimerization/desaturation of a carbapenam in an unusual process catalyzed by an iron- and 2-oxoglutarate-dependent oxygenase, CarC. Crystal structures of CarC complexed with Fe(II) and 2-oxoglutarate reveal it to be hexameric (space group C2221), consistent with solution studies. CarC monomers contain a double-stranded beta-helix core that supports ligands binding a single Fe(II) to which 2-oxoglutarate complexes in a bi-dentate manner. A structure was obtained with l-N-acetylproline acting as a substrate analogue. Quantum mechanical/molecular mechanical modeling studies with stereoisomers of carbapenams and carbapenems were used to investigate substrate binding. The combined work will stimulate further mechanistic studies and aid in the engineering of carbapenem biosynthesis.
authors.affiliation: Oxford Centre for Molecular Sciences and The Dyson Perrins Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Clifton
authors.forename: Linh X
authors.initials: LX
authors.lastname: Doan
authors.forename: Mark C
authors.initials: MC
authors.lastname: Sleeman
authors.forename: Maya
authors.initials: M
authors.lastname: Topf
authors.forename: Hikokazu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Rupert C
authors.initials: RC
authors.lastname: Wilmouth
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Schofield
mesh_terms: D001665:Binding Sites; D015780:Carbapenems / Q000096:biosynthesis*; D003461:Crystallography; D007501:Iron / Q000737:chemistry; D007656:Ketoglutaric Acids / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D016973:Pectobacterium carotovorum / Q000201:enzymology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: D015780:Carbapenems; D007656:Ketoglutaric Acids; D007501:Iron; D010088:Oxidoreductases; C022398:phytoene dehydrogenase