1Q19

Carbapenam Synthetase

Summary for 1Q19

• Entry DOI: 10.2210/pdb1q19/pdb
• Related: 1Q15
• Descriptor: CarA, MAGNESIUM ION, DIPHOSPHOMETHYLPHOSPHONIC ACID ADENOSYL ESTER, ... (5 entities in total)
• Functional Keywords: cmpr, (2s, 5s)-5-carboxymethylproline; b-ls, b-lactam synthetase; as-b, class b asparagine synthetase; amp-cpp, a, b-methyleneadenosine 5-triphosphate; cea, n2-(carboxyethyl)-l-arginine; cma, n2-(carboxylmethyl)-l-arginine, biosynthetic protein
• Biological source: Pectobacterium carotovorum
• Total number of polymer chains: 4
• Total formula weight: 227026.72

Authors

Miller, M.T.,Gerratana, B.,Stapon, A.,Townsend, C.A.,Rosenzweig, A.C. (deposition date: 2003-07-18, release date: 2003-11-04, Last modification date: 2023-08-16)

Primary citation

Miller, M.T.,Gerratana, B.,Stapon, A.,Townsend, C.A.,Rosenzweig, A.C.
Crystal Structure of Carbapenam Synthetase (CarA)
J.Biol.Chem., 278:40996-41002, 2003

PubMed Abstract: Carbapenam synthetase (CarA) is an ATP/Mg2+-dependent enzyme that catalyzes formation of the beta-lactam ring in (5R)-carbapenem-3-carboxylic acid biosynthesis. CarA is homologous to beta-lactam synthetase (beta-LS), which is involved in clavulanic acid biosynthesis. The catalytic cycles of CarA and beta-LS mediate substrate adenylation followed by beta-lactamization via a tetrahedral intermediate or transition state. Another member of this family of ATP/Mg2+-dependent enzymes, asparagine synthetase (AS-B), catalyzes intermolecular, rather than intramolecular, amide bond formation in asparagine biosynthesis. The crystal structures of apo-CarA and CarA complexed with the substrate (2S,5S)-5-carboxymethylproline (CMPr), ATP analog alpha,beta-methyleneadenosine 5'-triphosphate (AMP-CPP), and a single Mg2+ ion have been determined. CarA forms a tetramer. Each monomer resembles beta-LS and AS-B in overall fold, but key differences are observed. The N-terminal domain lacks the glutaminase active site found in AS-B, and an extended loop region not observed in beta-LS or AS-B is present. Comparison of the C-terminal synthetase active site to that in beta-LS reveals that the ATP binding site is highly conserved. By contrast, variations in the substrate binding pocket reflect the different substrates of the two enzymes. The Mg2+ coordination is also different. Several key residues in the active site are conserved between CarA and beta-LS, supporting proposed roles in beta-lactam formation. These data provide further insight into the structures of this class of enzymes and suggest that CarA might be a versatile target for protein engineering experiments aimed at developing improved production methods and new carbapenem antibiotics.

PubMed: 12890666
DOI: 10.1074/jbc.M307901200

Experimental method

X-RAY DIFFRACTION (2.4 Å)