2a7k

carboxymethylproline synthase (CarB) from pectobacterium carotovora, apo enzyme

spinqualitylabelsall models 2a7k, resolution 2.24Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2a7k is a 9 chain structure with sequence from Pectobacterium carotovorum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: CarB (Pectobacterium carotovorum) Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The first step in the biosynthesis of the medicinally important carbapenem family of beta-lactam antibiotics is catalyzed by carboxymethylproline synthase (CarB), a unique member of the crotonase superfamily. CarB catalyzes formation of (2S,5S)-carboxymethylproline [(2S,5S)-t-CMP] from malonyl-CoA and l-glutamate semialdehyde. In addition to using a cosubstrate, CarB catalyzes C-C and C-N bond formation processes as well as an acyl-coenzyme A hydrolysis reaction. We describe the crystal structure of CarB in the presence and absence of acetyl-CoA at 2.24 A and 3.15 A resolution, respectively. The structures reveal that CarB contains a conserved oxy-anion hole probably required for decarboxylation of malonyl-CoA and stabilization of the resultant enolate. Comparison of the structures reveals that conformational changes (involving His(229)) in the cavity predicted to bind l-glutamate semialdehyde occur on (co)substrate binding. Mechanisms for the formation of the carboxymethylproline ring are discussed in the light of the structures and the accompanying studies using isotopically labeled substrates; cyclization via 1,4-addition is consistent with the observed labeling results (providing that hydrogen exchange at the C-6 position of carboxymethylproline does not occur). The side chain of Glu(131) appears to be positioned to be involved in hydrolysis of the carboxymethylproline-CoA ester intermediate. Labeling experiments ruled out the possibility that hydrolysis proceeds via an anhydride in which water attacks a carbonyl derived from Glu(131), as proposed for 3-hydroxyisobutyryl-CoA hydrolase. The structural work will aid in mutagenesis studies directed at altering the selectivity of CarB to provide intermediates for the production of clinically useful carbapenems. Structural and mechanistic studies on carboxymethylproline synthase (CarB), a unique member of the crotonase superfamily catalyzing the first step in carbapenem biosynthesis.,Sleeman MC, Sorensen JL, Batchelar ET, McDonough MA, Schofield CJ J Biol Chem. 2005 Oct 14;280(41):34956-65. Epub 2005 Aug 11. PMID:16096274 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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