PDBsum entry 4qhc

Hydrolase/hydrolase inhibitor

PDB id: 4qhc

Contents

Protein chain

265 a.a.

Ligands

33V

PO4 ×2

Waters ×183

PDB id:

4qhc

Name:

Hydrolase/hydrolase inhibitor

Title:

Structure of m.Tuberculosis betalactamase (blac) with inhibitor having novel mechanism

Structure:

Beta-lactamase. Chain: a. Fragment: betalactam destroying enzyme. Synonym: penicillinase. Engineered: yes. Mutation: yes

Source:

Mycobacterium tuberculosis. Organism_taxid: 83332. Strain: atcc 25618 / h37rv. Gene: blaa, blac, rv2068c, mtcy49.07c. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.90Å R-factor: 0.163 R-free: 0.207

Authors:

S.Hazra,J.Blanchard

Key ref:

S.Hazra et al. (2015). Kinetic and Structural Characterization of the Interaction of 6-Methylidene Penem 2 with the β-Lactamase from Mycobacterium tuberculosis. Biochemistry, 54, 5657-5664. PubMed id: 26237118 DOI: 10.1021/acs.biochem.5b00698

Date:

28-May-14 Release date: 22-Jul-15

Protein chain

P9WKD3  (BLAC_MYCTU) -  Beta-lactamase from Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)

Seq: 307 a.a.

Struc: 265 a.a.

Enzyme reactions

• Enzyme class: E.C.3.5.2.6 - beta-lactamase.
• Pathway: Penicillin Biosynthesis and Metabolism
• Reaction: a beta-lactam + H2O = a substituted beta-amino acid
• Cofactor: Zn(2+)

DOI no: 10.1021/acs.biochem.5b00698

Biochemistry 54:5657-5664 (2015)

PubMed id: 26237118

Kinetic and Structural Characterization of the Interaction of 6-Methylidene Penem 2 with the β-Lactamase from Mycobacterium tuberculosis.

S.Hazra, S.G.Kurz, K.Wolff, L.Nguyen, R.A.Bonomo, J.S.Blanchard.

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.