N -Acetylglucosamine-1-Phosphate Transferase, WecA, as a Validated Drug Target in Mycobacterium tuberculosis

Abstract

The mycobacterial phosphoglycosyltransferase WecA, which initiates arabinogalactan biosynthesis in , has been proposed as a target of the caprazamycin derivative CPZEN-45, a preclinical drug candidate for the treatment of tuberculosis. In this report, we describe the functional characterization of mycobacterial WecA and confirm the essentiality of its encoding gene in by demonstrating that the transcriptional silencing of is bactericidal and in macrophages. Silencing also conferred hypersensitivity of to the drug tunicamycin, confirming its target selectivity for WecA in whole cells. Simple radiometric assays performed with mycobacterial membranes and commercially available substrates allowed chemical validation of other putative WecA inhibitors and resolved their selectivity toward WecA versus another attractive cell wall target, translocase I, which catalyzes the first membrane step in the biosynthesis of peptidoglycan. These assays and the mutant strain described herein will be useful for identifying potential antitubercular leads by screening chemical libraries for novel WecA inhibitors.

Liposidomycin, the first reported nucleoside antibiotic inhibitor of peptidoglycan biosynthesis translocase I: The discovery of liposidomycin and related compounds with a perspective on their application to new antibiotics

“…CPZEN-45 also inhibited WecA, which is involved in mycolylarabinogalactane biosynthesis in M. tuberculosis and is the ortholog of TagO (Fig. 2) [42,43,73], and this is an important result in terms of facilitating the development of new antituberculosis antibiotics.…”

“…such as M. tuberculosis exhibit cell wall structures with unusual complexity. The mycolyl-arabinogalactan-peptidoglycan (mAGP) complex represents the cell wall core structure creating a lipophilic pseudo-outer membrane [2,10,42,43] (Fig. 2).…”

“…because of the limited permeability of antibiotics through their outer membranes. In the biosynthetic pathway of peptidoglycan and mycolyl-arabinogalactan in M. tuberculosis, the membrane proteins translocase I (MurX: the ortholog of MraY in various bacteria) and WecA (polyprenyl phosphate-Nacetylglucosamine-1-phosphate transferase; the ortholog of TagO in Bacillus subtilis) are involved and are important drug targets [43]. Caprazamycin inhibits the former enzyme and CPZEN-45 inhibits the latter enzyme, as described in Section "Caprazamycin, A-90289A, and muraminomycin as liposidomycin analogs with specific MraY inhibition activity" (Fig.…”

“…In the case of mureidomycin A, a translocase I inhibitor, the intrinsic resistance of bacteria is due to low permeability [44]. TB drug resistance has emphasized the need to identify new targets for antibiotic action that lack cross resistance to existing therapies, such as inhibitors of translocase I [10,11,15,43].…”

Antibiotics and resistance: the two-sided coin of the mycobacterial cell wall

“…The caprazamycin derivative, CPZEN-45, inhibits WecA ( Ishizaki et al, 2013 ), an essential protein involved in the synthesis of the unique rhamnose-GlcNAc linker between AG and PG ( Huszár et al, 2017 , Jin et al, 2010 ). While CPZEN-45 has good pharmacological properties and is active against MDR strains, it has poor bioavailability and so is currently being trialled for inhalation therapy in combination with the unrelated second-line drug, capreomycin ( Pitner et al, 2019 ).…”