Crystal Structure of the IMP-1 Metallo -Lactamase from Pseudomonas aeruginosa and Its Complex with a Mercaptoc

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• 作者：Né ; stor O. Concha ; Cheryl A. Janson ; Pam Rowling ; Stewart Pearson ; Christy A. Cheever ; Brian P. Clarke ; Ceri Lewis ; Moreno Galleni ; Jean-Marie Frè ; re ; David J. Payne ; John H. Bateson ; and
• 刊名：Biochemistry
• 出版年：2000
• 出版时间：April 18, 2000
• 年：2000
• 卷：39
• 期：15
• 页码：4288 - 4298
• 全文大小：675K
• 年卷期：v.39,no.15(April 18, 2000)
• ISSN：1520-4995

文摘

Metallo mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamase enzymes confer antibiotic resistance to bacteria by catalyzing the hydrolysisof mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactam antibiotics. This relatively new form of resistance is spreading unchallenged as there is acurrent lack of potent and selective inhibitors of metallo mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamases. Reported here are the crystalstructures of the native IMP-1 metallo mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamase from Pseudomonas aeruginosa and its complex witha mercaptocarboxylate inhibitor, 2-[5-(1-tetrazolylmethyl)thien-3-yl]-N-[2-(mercaptomethyl)-4-(phenylbutyrylglycine)]. The structures were determined by molecular replacement, and refined to 3.1 Å (native)and 2.0 Å (complex) resolution. Binding of the inhibitor in the active site induces a conformational changethat results in closing of the flap and transforms the active site groove into a tunnel-shaped cavity enclosing83% of the solvent accessible surface area of the inhibitor. The inhibitor binds in the active site throughinteractions with residues that are conserved among metallo mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamases; the inhibitor's carboxylategroup interacts with Lys161, and the main chain amide nitrogen of Asn167. In the "oxyanion hole", theamide carbonyl oxygen of the inhibitor interacts through a water molecule with the side chain of Asn167,the inhibitor's thiolate bridges the two Zn(II) ions in the active site displacing the bridging water, and thephenylbutyryl side chain binds in a hydrophobic pocket (S1) at the base of the flap. The flap is displaced2.9 Å compared to the unbound structure, allowing Trp28 to interact edge-to-face with the inhibitor'sthiophene ring. The similarities between this inhibitor and the mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactam substrates suggest a mode ofsubstrate binding and the role of the conserved residues in the active site. It appears that the metallomages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamases bind their substrates by establishing a subset of binding interactions near the catalytic centerwith conserved characteristic chemical groups of the mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactam substrates. These interactions arecomplemented by additional nonspecific binding between the more variable groups in the substrates andthe flexible flap. This unique mode of binding of the mercaptocarboxylate inhibitor in the enzyme activesite provides a binding model for metallo mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactamase inhibition with utility for future drug design.