Addressing Antimicrobial Resistance in Mycobacterium tuberculosis - A Structure-Guided Campaign Against Cytochrome P450s CYP121A1, CYP141A1 and CYP143A1

  • Irwin Selvam

Student thesis: Phd

Abstract

TB remains a leading cause of death worldwide and the continued spread of drug-resistance is threatening the progress made in controlling its transmission. Thus, there is an urgent need for novel antitubercular compounds. In the present work, three members of the cytochrome P450 (CYP) family present in Mycobacterium tuberculosis, CYP121A1 and the orphans CYP141A1 and CYP143A1, were studied as putative drug targets. A structure-guided campaign against CYP121A1, in combination with phenotypic screening, yielded a number of promising compounds. In particular, a benzo[b][1,4]oxazine derivative, displayed pan-assay activity against Mtb H37Rv in culture (MIC90 6.25 µM) and is a suitable starting point for further lead-to-clinical development. Separate work generated an array of substrate-like analogues for CYP121A1, two of which displayed low µM affinity for CYP121A1 and thus may be suitable starting points for further medicinal chemistry. The X-ray crystal structures of ligand-free CYP141A1 and PEG-bound CYP143A1 were determined at 2.05 and 1.54 Å respectively. CYP141A1 adopts a ‘closed’ state in crystallo, whereas mobile loops in CYP143A1 are positioned to give free access to the heme-b prosthetic group. Both proteins were subjected to fragment-based screening and the resulting hits will allow for the development of novel inhibitors of CYP141A1 and CYP143A1. Initial substrate screening for CYP141A1 and CYP143A1 has eliminated a variety of candidate substrates. The results described in this work contribute towards the body of knowledge surrounding the Mtb CYPs and provide starting points for more involved medicinal chemistry. In addition, mechanistic studies of CYP121A1 utilizing transition-state analogues may shed light on the unusual carbon-carbon coupling reaction it catalyzes.
Date of Award1 Aug 2023
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorAndrew Munro (Supervisor), David Leys (Supervisor) & Jonathan Waltho (Supervisor)

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