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Acetylene containing cyclo(L-Tyr-L-Tyr)-analogs as mechanism-based inhibitors of CYP121A1 from Mycobacterium tuberculosis

Authors :
Alexander Speer
Kerstin Wallraven
Sandra Ortega Ugalde
Tom N. Grossmann
Jan N. M. Commandeur
Wilbert Bitter
Molecular and Computational Toxicology
Organic Chemistry
Molecular Microbiology
AIMMS
Medical Microbiology and Infection Prevention
AII - Infectious diseases
Source :
Ortega Ugalde, S, Wallraven, K, Speer, A, Bitter, W, Grossmann, T N & Commandeur, J N M 2020, ' Acetylene containing cyclo(L-Tyr-L-Tyr)-analogs as mechanism-based inhibitors of CYP121A1 from Mycobacterium tuberculosis ', Biochemical Pharmacology, vol. 177, 113938, pp. 113938 . https://doi.org/10.1016/j.bcp.2020.113938, Biochemical Pharmacology, 177:113938, 1-14. Elsevier Inc., Biochemical Pharmacology, 177:113938. Elsevier Inc., Ortega Ugalde, S, Wallraven, K, Speer, A, Bitter, W, Grossmann, T N & Commandeur, J N M 2020, ' Acetylene containing cyclo(L-Tyr-L-Tyr)-analogs as mechanism-based inhibitors of CYP121A1 from Mycobacterium tuberculosis ', Biochemical Pharmacology, vol. 177, 113938, pp. 1-14 . https://doi.org/10.1016/j.bcp.2020.113938
Publication Year :
2020

Abstract

Tuberculosis (TB) is a globally significant infective disease that is caused by a single infectious agent, Mycobacterium tuberculosis (Mtb). Because of the rise in the number of multidrug-resistant (MDR) TB strains, identification of alternative drug targets for the development of drugs with different mechanism of actions is desired. CYP121A1, one of the twenty cytochrome P450 enzymes encoded in the Mtb genome, was previously shown to be essential for bacterial growth. This enzyme catalyzes the intramolecular C–C crosslinking reaction of the cyclopeptide cyclo(L-tyr-L-tyr) (cYY) yielding the metabolite mycocyclosin. In the present study, acetylene-substituted cYY-analogs were synthesized and evaluated as potential mechanism-based inhibitors of CYP121A1. The acetylene-substituted cYY-analogs were capable of binding to CYP121A1 with affinities comparable with cYY, and exhibited a Type I binding mode, indicative of a substrate-like binding, mandatory for metabolism. Only the cYY-analogs which contain an acetylene-substitution at one (2a) or both (3) para-positions of cYY showed mechanism-based inhibition of CYP121A1 activity. The values of KI and kinact were 236 µM and 0.045 min−1, respectively, for compound 2a, and 145 µM and 0.015 min−1, repectively, for compound 3 The inactivation could neither be reversed by dialysis nor be prevented by including glutathione. LC-MS analysis demonstrated that the inactivation results from covalent binding to the apoprotein, whereas the heme was unmodified. Interestingly, the mass increment of the CYP121A1 apoprotein was significantly smaller than was expected from the ketene formed by oxidation of the acetylene-group, indicative for a secondary cleavage reaction in the active site of CYP121A1. Although the two acetylene-containing cYY-analogs showed significant mechanism-based inhibition, growth inhibition of the Mtb strains was only observed at millimolar concentrations. This low efficacy may be due to insufficient irreversible inactivation of CYP121A1 and/or insufficient cellular uptake. Although the identified mechanism-based inhibitors have no perspective for Mtb-treatment, this study is the first proof-of-principle that mechanism-based inhibition of CYP121A1 is feasible and may provide the basis for new strategies in the design and development of compounds against this promising therapeutic target.

Details

Language :
English
ISSN :
00062952
Volume :
177
Database :
OpenAIRE
Journal :
Biochemical Pharmacology
Accession number :
edsair.doi.dedup.....07b4d2df84378e08e1bf262981ea247f
Full Text :
https://doi.org/10.1016/j.bcp.2020.113938