A multitarget approach to drug discovery inhibiting Mycobacterium tuberculosis PyrG and PanK

Abstract

Mycobacterium tuberculosis, the etiological agent of the infectious disease tuberculosis, kills approximately 1.5 million people annually, while the spread of multidrug-resistant strains is of great global concern. Thus, continuous efforts to identify new antitubercular drugs as well as novel targets are crucial. Recently, two prodrugs activated by the monooxygenase EthA, 7947882 and 7904688, which target the CTP synthetase PyrG, were identified and characterized. In this work, microbiological, biochemical, and in silico methodologies were used to demonstrate that both prodrugs possess a second target, the pantothenate kinase PanK. This enzyme is involved in coenzyme A biosynthesis, an essential pathway for M. tuberculosis growth. Moreover, compound 11426026, the active metabolite of 7947882, was demonstrated to directly inhibit PanK, as well. In an independent screen of a compound library against PyrG, two additional inhibitors were also found to be active against PanK. In conclusion, these direct PyrG and PanK inhibitors can be considered as leads for multitarget antitubercular drugs and these two enzymes could be employed as a “double-tool” in order to find additional hit compounds.

A Small Molecule Inhibitor of CTP Synthetase Identified by Differential Activity on a Bacillus subtilis Mutant Deficient in Class A Penicillin-Binding Proteins

“…Not surprisingly, the pyrG gene encoding CTPS has been shown to be essential in several different organisms (e.g., Kobayashi et al, 2003 ; Mori et al, 2015 ). CTPS has indeed been explored as a potential therapeutic target for a number of infections, especially Mycobacterium tuberculosis ( Mori et al, 2015 ; Esposito et al, 2017 ; Chiarelli et al, 2018 ), but also for protozoan infections including trypanosomiasis ( Fijolek et al, 2007 ). Nucleoside analogs acting on CTPS have also been used in human cancer therapies e.g., gemcitabine ( Mccluskey et al, 2016 ); but these tend to have complex off target effects as they can interfere with multiple nucleotide binding proteins and even act as substrates.…”

Structure-Guided Computational Approaches to Unravel Druggable Proteomic Landscape of Mycobacterium leprae

“…Finally, we modeled coaA which synthesizes coA from (R)-Pantothenate. CoaA has been recognized as a drug target in tuberculosis (Chiarelli et al, 2018). We modeled coaA using its orthologue in M. tuberculosis (PDB Id: 2GET) as the template with sequence identity of 93% and sequence coverage of 98% (Figure 2C).…”

Mycobacterial drug discovery

“…WGS of laboratory-generated spontaneous resistant mutants is routinely used to identify mutations within the target gene, which enables the resistance phenotype. [35][36][37][38] Target identification in this way is not always possible, with examples including: 1) if mutations occur in genes responsible for the resistance mechanism, such as the up-regulation of efflux pumps 39 or mutations in pro-drug activators; 40,41 2) if there is more than one target; 42 3) if the target is not a protein (such as the cell wall structural targets of nisin and vancomycin); 4) if spontaneous resistant mutant generation is not possible. In these circumstances, target deconvolution becomes a challenging process, but not impossible.…”