Structural Basis for the Inhibition of Mycobacterium tuberculosis Glutamine Synthetase by Novel ATP-Competitive Inhibitors

JOURNAL OF MOLECULAR BIOLOGY

卷:393

Article

Nilsson, Mikael T.²  Krajewski, Wojciech W.²  Yellagunda, Sujan³  Prabhumurthy, Savitha³  Chamarahally, Gayathri N.³  Siddamadappa, Chandrasekharan³  Srinivasa, Bachally R.³  Yahiaoui, Samir⁴  Larhed, Mats⁴  Karlen, Anders⁴  Jones, T. Alwyn²  Mowbray, Sherry L.¹ 

[1] Swedish Univ Agr Sci, Dept Mol Biol, Biomed Ctr, SE-75124 Uppsala, Sweden

[2] Uppsala Univ, Dept Cell & Mol Biol, Biomed Ctr, SE-75124 Uppsala, Sweden

[3] AstraZeneca India Private Ltd, Bangalore 560024, Karnataka, India

[4] Uppsala Univ, Dept Med Chem, Biomed Ctr, SE-75123 Uppsala, Sweden

关键词: glutamine synthetase;    X-ray crystallography;    high-throughput screening;    drug design;    tuberculosis;   

DOI  :  10.1016/j.jmb.2009.08.028

来源: Elsevier

【 摘 要 】

Glutamine synthetase (GS, EC 6.3.1.2; also known as gamma-glutamyl:ammonia ligase) catalyzes the ATP-dependent condensation of glutamate and ammonia to form glutamine. The enzyme has essential roles in different tissues and species, which have led to its consideration as a drug or an herbicide target. In this article, we describe studies aimed at the discovery of new antimicrobial agents targeting Mycobacterium tuberculosis, the causative pathogen of tuberculosis. A number of distinct classes of GS inhibitors with an IC50 of micromolar value or better were identified via high-throughput screening. A commercially available purine analogue similar to one of the clusters identified (the diketopurines), 1-[(3,4-dichlorophenyl)methyl]-3,7-dimethyl-8-morpholin-4-yl-purine-2,6-dione, was also shown to inhibit the enzyme, with a measured IC50 of 2.5+/-0.4 mu M. Two X-ray structures are presented: one is a complex of the enzyme with the purine analogue alone (2.55-angstrom resolution), and the other includes the compound together with methionine sulfoximine phosphate, magnesium and phosphate (2.2-angstrom resolution). The former represents a relaxed, inactive conformation of the enzyme, while the latter is a taut, active one. These structures show that the compound binds at the same position in the nucleotide site, regardless of the conformational state. The ATP-binding site of the human enzyme differs substantially, explaining why it has an similar to 60-fold lower affinity for this compound than the bacterial GS. As part of this work, we devised a new synthetic procedure for generating L-(SR)-methionine sulfoximine phosphate from L-(SR)-methionine sulfoximine, which will facilitate future investigations of novel GS inhibitors. (C) 2009 Elsevier Ltd. All rights reserved.

【 授权许可】

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