Inactivation of the Mycobacterium tuberculosis Antigen 85 Complex by Covalent, Allosteric Inhibitors

Abstract

Background:The antigen 85 complex represents three homologous mycolyltransferases that show promise as tuberculosis drug targets. Results: Structures of antigen 85C (Ag85C) covalently modified at a conserved cysteine and Ag85C active site mutants exhibit disruption of the active site structure. Conclusion: Structural dynamics are important for Ag85C function and inhibition. Significance: Targeted thiol modification of the antigen 85 complex is a valid inhibitory mechanism for inhibitor design.

An Antibacterial β‐Lactone Kills Mycobacterium tuberculosis by Disrupting Mycolic Acid Biosynthesis

“…As expected, INH almost completely abolished 13 Ci ncorporation. EZ120 treatment reduced 13 Ci ncorporation in ad ose-dependent manner but not as strongly as INH ( Figure 4E). Nevertheless,the results indicate that the inhibition of MA synthesis was the result of the treatment.…”

“…[11] Although individual Ag85 genes are dispensable,l oss of at least two is lethal. [12] Crystal structures of the orthologous proteins exhibit conserved active sites, [13] and treatment with inhibitors,s uch as ebselen, result in decreasing TDM levels and accumulation of TMM. [14] Given the crucial role of diverse serine hydrolases in mycomembrane biosynthesis and their binding of mycolates as b-keto or -hydroxy esters ( Figure 1B), we rationalized that long-chain aliphatic compounds equipped with an electrophilic group could act as covalent inhibitors of several of these key steps.…”

“…To avoid 14 Cl abeling in the biosafety level 3l aboratory,w e developed an ew MS-based 13 C labeling method. We biosynthetically labeled Mtb lipids by supplementing [1,[2][3][4][5][6][7][8][9][10][11][12][13] C] acetate in media for 48 h. MAs were analyzed after saponification by negative-mode HPLC-MS,a nd the 13 C-labeled MAs showed ac omplex profile compared to the unlabeled sample ( Figure 4A). This complexity stems from MA molecules containing different functional groups throughout the molecule,a swell as overlapping isotope peaks derived from endogenous and supplemented 13 C( see the Supporting Information for details).…”

Ebselen, a Small-Molecule Capsid Inhibitor of HIV-1 Replication

“…Previous studies show that this compound forms a covalent bond between its selenium atom and thiols in cysteine residues by forming a selenylsulfide (-Se-S-) linkage (27)(28)(29). HIV-1 capsid contains two cysteine residues, Cys198 and Cys218 (full-length CA numbering), both located in the CTD.…”

“…Taken together, these results demonstrate that ebselen has no impact on late events in the HIV-1 life cycle. (27)(28)(29), ebselen forms a selenylsulfide (-Se-S-) linkage with cysteine residues. To confirm the importance of the selenium atom in ebselen, we analyzed analogs with selenium replaced by sulfur (S-ebselen), oxygen (O-ebselen), carbon (C-ebselen) (40), or a selenoxide group (ebselen oxide) or with the phenyl ring converted to pyridine (2pyr-ebselen and 3pyr-ebselen) (41) ( Table 1).…”