4QHC

Structure of M.Tuberculosis Betalactamase (Blac) with inhibitor having novel mechanism

Summary for 4QHC

• Entry DOI: 10.2210/pdb4qhc/pdb
• Related: 4DF6 4Q8I 4QB8
• Descriptor: Beta-lactamase, (3R,6R,7S)-7-[(2R,3aR)-hexahydropyrazolo[1,5-c][1,3]thiazin-2-yl]-6-(hydroxymethyl)-1,4-thiazepane-3-carboxylic acid, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: betalactam, betalactamase, penems, drug resistance, novel mechanism, qm/mm, 3-layer sandwich, dd-peptidase, beta-lactamase super family, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Mycobacterium tuberculosis
• Cellular location: Cell inner membrane : P9WKD3
• Total number of polymer chains: 1
• Total formula weight: 28867.21

Authors

Hazra, S.,Blanchard, J. (deposition date: 2014-05-28, release date: 2015-07-22, Last modification date: 2024-02-28)

Primary citation

Hazra, S.,Kurz, S.G.,Wolff, K.,Nguyen, L.,Bonomo, R.A.,Blanchard, J.S.
Kinetic and Structural Characterization of the Interaction of 6-Methylidene Penem 2 with the beta-Lactamase from Mycobacterium tuberculosis.
Biochemistry, 54:5657-5664, 2015

PubMed Abstract: Mycobacterium tuberculosis is intrinsically resistant to most β-lactam antibiotics because of the constitutive expression of the blaC-encoded β-lactamase. This enzyme has extremely high activity against penicillins and cephalosporins, but weaker activity against carbapenems. The enzyme can be inhibited by clavulanate, avibactam, and boronic acids. In this study, we investigated the ability of 6-methylidene β-lactams to inhibit BlaC. One such compound, penem 2, inhibited BlaC more than 70 times more efficiently than clavulanate. The compound forms a covalent complex with BlaC as shown by mass spectrometry. Crystallization of the complex revealed that the bound inhibitor was covalently attached via the Ser70 active site residue and that the covalently, acylated form of the inhibitor had undergone additional chemistry yielding a 4,7-thiazepine ring in place of the β-lactam and a thiazapyroline ring generated as a result of β-lactam ring opening. The stereochemistry of the product of the 7-endo-trig cyclization was the opposite of that observed previously for class A and D β-lactamases. Addition of penem 2 greatly synergized the antibacterial properties of both ampicillin and meropenem against a growing culture of M. tuberculosis. Strikingly, penem 2 alone showed significant growth inhibition, suggesting that in addition to its capability of efficiently inhibiting BlaC, it also inhibited the peptidoglycan cross-linking transpeptidases.

PubMed: 26237118
DOI: 10.1021/acs.biochem.5b00698

Experimental method

X-RAY DIFFRACTION (1.899 Å)