2AIO

Metallo beta lactamase L1 from Stenotrophomonas maltophilia complexed with hydrolyzed moxalactam

Summary for 2AIO

• Entry DOI: 10.2210/pdb2aio/pdb
• Related: 1sml
• Descriptor: Metallo-beta-lactamase L1, ZINC ION, SULFATE ION, ... (5 entities in total)
• Functional Keywords: alpha-beta/beta-alpha fold, metallo-beta-lactamase, hydrolase, binuclear
• Biological source: Stenotrophomonas maltophilia
• Cellular location: Periplasm (Potential): P52700
• Total number of polymer chains: 1
• Total formula weight: 29389.68

Authors

Spencer, J.,Read, J.,Sessions, R.B.,Howell, S.,Blackburn, G.M.,Gamblin, S.J. (deposition date: 2005-07-30, release date: 2005-10-11, Last modification date: 2024-11-13)

Primary citation

Spencer, J.,Read, J.,Sessions, R.B.,Howell, S.,Blackburn, G.M.,Gamblin, S.J.
Antibiotic Recognition by Binuclear Metallo-beta-Lactamases Revealed by X-ray Crystallography
J.Am.Chem.Soc., 127:14439-14444, 2005

PubMed Abstract: Metallo-beta-lactamases are zinc-dependent enzymes responsible for resistance to beta-lactam antibiotics in a variety of host bacteria, usually Gram-negative species that act as opportunist pathogens. They hydrolyze all classes of beta-lactam antibiotics, including carbapenems, and escape the action of available beta-lactamase inhibitors. Efforts to develop effective inhibitors have been hampered by the lack of structural information regarding how these enzymes recognize and turn over beta-lactam substrates. We report here the crystal structure of the Stenotrophomonas maltophilia L1 enzyme in complex with the hydrolysis product of the 7alpha-methoxyoxacephem, moxalactam. The on-enzyme complex is a 3'-exo-methylene species generated by elimination of the 1-methyltetrazolyl-5-thiolate anion from the 3'-methyl group. Moxalactam binding to L1 involves direct interaction of the two active site zinc ions with the beta-lactam amide and C4 carboxylate, groups that are common to all beta-lactam substrates. The 7beta-[(4-hydroxyphenyl)malonyl]-amino substituent makes limited hydrophobic and hydrogen bonding contacts with the active site groove. The mode of binding provides strong evidence that a water molecule situated between the two metal ions is the most likely nucleophile in the hydrolytic reaction. These data suggest a reaction mechanism for metallo-beta-lactamases in which both metal ions contribute to catalysis by activating the bridging water/hydroxide nucleophile, polarizing the substrate amide bond for attack and stabilizing anionic nitrogen intermediates. The structure illustrates how a binuclear zinc site confers upon metallo-beta-lactamases the ability both to recognize and efficiently hydrolyze a wide variety of beta-lactam substrates.

PubMed: 16218639
DOI: 10.1021/ja0536062

Experimental method

X-RAY DIFFRACTION (1.7 Å)