Browsing by Author "Kalia, Nitin P."

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Carbon metabolism modulates the efficacy of drugs targeting the cytochrome bc1:aa3 in Mycobacterium tuberculosis
(2019-06) Kalia, Nitin P.; Shi Lee, Bei; Ab Rahman, Nurlilah B.; Moraski, Garrett C.; Miller, Marvin J.; Pethe, Kevin
The influence of carbon metabolism on oxidative phosphorylation is poorly understood in mycobacteria. M. tuberculosis expresses two respiratory terminal oxidases, the cytochrome bc1:aa3 and the cytochrome bd oxidase, which are jointly required for oxidative phosphorylation and mycobacterial viability. The essentiality of the cytochrome bc1:aa3 for optimum growth is illustrated by its vulnerability to chemical inhibition by the clinical drug candidate Q203 and several other chemical series. The cytochrome bd oxidase is not strictly essential for growth but is required to maintain bioenergetics when the function of the cytochrome bc1:aa3 is compromised. In this study, we observed that the potency of drugs targeting the cytochrome bc1:aa3 is influenced by carbon metabolism. The efficacy of Q203 and related derivatives was alleviated by glycerol supplementation. The negative effect of glycerol supplementation on Q203 potency correlated with an upregulation of the cytochrome bd oxidase-encoding cydABDC operon. Upon deletion of cydAB, the detrimental effect of glycerol on the potency of Q203 was abrogated. The same phenomenon was also observed in recent clinical isolates, but to a lesser extent compared to the laboratory-adapted strain H37Rv. This study reinforces the importance of optimizing in vitro culture conditions for drug evaluation in mycobacteria, a factor which appeared to be particularly essential for drugs targeting the cytochrome bc1:aa3 terminal oxidase.
Dual inhibition of the terminal oxidases eradicates antibiotic‐tolerant Mycobacterium tuberculosis
(EMBO, 2020-12) Lee, Bei Shi; Hards, Kiel; Engelhart, Curtis A.; Hasenoehrl, Erik J.; Kalia, Nitin P.; Mackenzie, Jared S.; Sviriaeva, Ekaterina; Chong, Shi Min Sherilyn; Manimekalai, Sony S.; Koh, Vanessa H.; Xu, Jiayong; Alonso, Sylvie; Miller, Marvin J.; Steyn, Adrie J.C.; Gruber, Gerhard; Schnappinger, Dirk; Berney, Michael; Cook, Gregory M.; Moraski, Garrett C.; Pethe, Kevin
The approval of bedaquiline has placed energy metabolism in the limelight as an attractive target space for tuberculosis antibiotic development. While bedaquiline inhibits the mycobacterial F1F0 ATP synthase, small molecules targeting other components of the oxidative phosphorylation pathway have been identified. Of particular interest is Telacebec (Q203), a phase 2 drug candidate inhibitor of the cytochrome bcc:aa3 terminal oxidase. A functional redundancy between the cytochrome bcc:aa3 and the cytochrome bd oxidase protects M. tuberculosis from Q203-induced death, highlighting the attractiveness of the bd-type terminal oxidase for drug development. Here, we employed a facile whole-cell screen approach to identify the cytochrome bd inhibitor ND-011992. Although ND-011992 is ineffective on its own, it inhibits respiration and ATP homeostasis in combination with Q203. The drug combination was bactericidal against replicating and antibiotictolerant, non-replicating mycobacteria, and increased efficacy relative to that of a single drug in a mouse model. These findings suggest that a cytochrome bd oxidase inhibitor will add value to a drug combination targeting oxidative phosphorylation for tuberculosis treatment.
Structure guided generation of thieno[3,2-d]pyrimidin-4-amine Mycobacterium tuberculosis bd oxidase inhibitors
(Royal Society of Chemistry, 2021-01) Hopfner, Sarah M.; Lee, Bei Shi; Kalia, Nitin P.; Miller, Marvin J.; Pethe, Kevin; Moraski, Garrett C.
Screening for inhibitors of Cyt-bd in Mycobacterium bovis BCG and Mycobacterium tuberculosis revealed thieno[3,2-d]pyrimidine (7) which through SAR efforts resulted in an improved analogue (19) of this scaffold.
Syntheses and Structure–Activity Relationships of N-Phenethyl-Quinazolin-4-yl-Amines as Potent Inhibitors of Cytochrome bd Oxidase in Mycobacterium tuberculosis
(MDPI, 2021-09) Hopfner, Sarah M.; Lee, Bei Shi; Kalia, Nitin P.; Miller, Marvin J.; Pethe, Kevin; Moraski, Garrett C.
The development of cytochrome bd oxidase (cyt-bd) inhibitors are needed for comprehensive termination of energy production in Mycobacterium tuberculosis (Mtb) to treat tuberculosis infections. Herein, we report on the structure-activity-relationships (SAR) of 22 new N-phenethyl-quinazolin-4-yl-amines that target cyt-bd. Our focused set of compounds was synthesized and screened against three mycobacterial strains: Mycobacterium bovis BCG, Mycobacterium tuberculosis H37Rv and the clinical isolate Mycobacterium tuberculosis N0145 with and without the cytochrome bcc:aa3 inhibitor Q203 in an ATP depletion assay. Two compounds, 12a and 19a, were more active against all three strains than the naturally derived cyt-bd inhibitor aurachin D.