Kinetic analyses of the siderophore biosynthesis inhibitor salicyl-AMS and analogues as MbtA inhibitors and antimycobacterial agents Journal Article


Authors: Bythrow, G. V.; Mohandas, P.; Guney, T.; Standke, L. C.; Germain, G. A.; Lu, X.; Ji, C.; Levendosky, K.; Chavadi, S. S.; Tan, D. S.; Quadri, L. E. N.
Article Title: Kinetic analyses of the siderophore biosynthesis inhibitor salicyl-AMS and analogues as MbtA inhibitors and antimycobacterial agents
Abstract: There is a paramount need for expanding the drug armamentarium to counter the growing problem of drug-resistant tuberculosis. Salicyl-AMS, an inhibitor of salicylic acid adenylation enzymes, is a first-in-class antibacterial lead compound for the development of tuberculosis drugs targeting the biosynthesis of salicylic-acid-derived siderophores. In this study, we determined the K i of salicyl-AMS for inhibition of the salicylic acid adenylation enzyme MbtA from Mycobacterium tuberculosis (MbtA tb ), designed and synthesized two new salicyl-AMS analogues to probe structure-activity relationships (SAR), and characterized these two analogues alongside salicyl-AMS and six previously reported analogues in biochemical and cell-based studies. The biochemical studies included determination of kinetic parameters (Ki app , kon app , k off , and t R ) and analysis of the mechanism of inhibition. For these studies, we optimized production and purification of recombinant MbtA tb , for which K m and k cat values were determined, and used the enzyme in conjunction with an MbtA tb -optimized, continuous, spectrophotometric assay for MbtA activity and inhibition. The cell-based studies provided an assessment of the antimycobacterial activity and postantibiotic effect of the nine MbtA tb inhibitors. The antimycobacterial properties were evaluated using a strain of nonpathogenic, fast-growing Mycobacterium smegmatis that was genetically engineered for MbtA tb -dependent susceptibility to MbtA inhibitors. This convenient model system greatly facilitated the cell-based studies by bypassing the methodological complexities associated with the use of pathogenic, slow-growing M. tuberculosis. Collectively, these studies provide new information on the mechanism of inhibition of MbtA tb by salicyl-AMS and eight analogues, afford new SAR insights for these inhibitors, and highlight several suitable candidates for future preclinical evaluation. © 2018 American Chemical Society.
Keywords: enzyme inhibition; biosynthesis; mycobacterium tuberculosis; biochemistry; mycobacterium smegmatis; biochemical studies; bacteria; salicylic acid; lead compounds; anti-mycobacterial; antimycobacterial activity; biosynthesis inhibitors; optimized production; spectrophotometric assays
Journal Title: Biochemistry
Volume: 58
Issue: 6
ISSN: 0006-2960
Publisher: American Chemical Society  
Date Published: 2019-02-12
Start Page: 833
End Page: 847
Language: English
DOI: 10.1021/acs.biochem.8b01153
PUBMED: 30582694
PROVIDER: scopus
PMCID: PMC6530907
DOI/URL:
Notes: Article -- Export Date: 1 March 2019 -- Source: Scopus
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MSK Authors
  1. Xuequan Lu
    7 Lu
  2. Derek S Tan
    74 Tan
  3. Cheng   Ji
    4 Ji
  4. Tezcan   Guney
    5 Guney