Characterization of OJT008 As a Novel Inhibitor ofMycobacterium tuberculosis

Abstract

<b>Abstract ID 26564</b> <b>Poster Board 94</b> Despite recent progress in the diagnosis of Tuberculosis (TB), the chemotherapeutic management of TB is still challenging. <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>) is the etiological agent of TB, and TB is classified as the 13th leading cause of death globally. It is estimated that 558,000 people were reported to develop multi-drug resistant TB globally. Our research focuses on targeting Methionine Aminopeptidase (MetAP), an essential protein for the viability of <i>Mtb</i>. MetAP is a metalloprotease that catalyzes the N-terminal methionine excision (NME) during protein synthesis. This essential role of MetAPs allows this enzyme an auspicious target for the development of novel therapeutic agents for the treatment of TB. <i>Mtb</i> possesses 2 MetAP1 isoforms: MtMetAP1a and MtMetAP1c. In our study, we cloned, overexpressed recombinant MtMetAP1c, and investigated the <i>in&nbsp;vitro</i> inhibitory effect of OJT008 on cobalt and nickel ion activated MtMetAP1c and the mechanism of action was elucidated through an <i>in-silico</i> approach. The compound’s potency against replicating and multidrug-resistant (MDR) <i>Mtb</i> strains was also investigated. The induction of the overexpressed recombinant MtMetAP1c was optimized at 8 hours with a final concentration of 1mM Isopropyl β-D-1-thiogalactopyranoside. The average yield for MtMetAP1c was 4.65mg mg/L of <i>Escherichia coli</i> culture. A preliminary MtMetAP1c metal dependency screen Providedoptimum activation with nickel and cobalt ions at 100μM. The half maximal inhibitory concentration (IC₅₀) values of OJT008 against MtMetAP1c activated with CoCl₂ and NiCl₂ were 11μM and 40 μM respectively. The <i>in-silico</i> study showed OJT008 strongly binds to both metals activated MtMetAP1c, as evidenced by strong molecular interactions and higher binding score thereby corroborating our result. This <i>in-silico</i> study validated the pharmacophore’s metal specificity. The potency of OJT008 against drug sensitive and MDR <i>Mtb</i> was &lt; 0.063 μg/mL. Our study reports OJT008 as an inhibitor of MtMetAP1c which is potent at low micromolar concentrations against both drug-sensitive and MDR-<i>Mtb</i>. These results suggest OJT008 is a potential lead compound for the development of novel small molecules for the therapeutic management of TB. This project is sponsored by NIH-RCMI (U54MD007605) Grants.