Benzothiazinones Are Suicide Inhibitors of Mycobacterial Decaprenylphosphoryl-β-

Benzothiazinones (BTZs) are antituberculosis drug candidates with nanomolar bactericidal activity against tubercle bacilli. Here we demonstrate that BTZs are suicide substrates of the FAD-dependent decaprenylphosphoryl-beta-D-ribofuranose 2'-oxidase DprE1, an enzyme involved in cell-wall biogenesis. BTZs are reduced by DprE1 to an electrophile, which then reacts in a near-quantitative manner with an active-site cysteine of DprE1, thus providing a rationale for the extraordinary potency of BTZs. Mutant DprE1 enzymes from BTZ-resistant strains reduce BTZs to inert metabolites while avoiding covalent inactivation. Our results explain the basis for drug sensitivity and resistance to an exceptionally potent class of antituberculosis agents

Identification of a small molecule with activity against drug-resistant and persistent tuberculosis

A cell-based phenotypic screen for inhibitors of biofilm formation in mycobacteria identified the small molecule TCA1, which has bactericidal activity against both drug-susceptible and -resistant Mycobacterium tuberculosis (Mtb) and sterilizes Mtb in vitro combined with rifampicin or isoniazid. In addition, TCA1 has bactericidal activity against nonreplicating Mtb in vitro and is efficacious in acute and chronic Mtb infection mouse models both alone and combined with rifampicin or isoniazid. Transcriptional analysis revealed that TCA1 down-regulates genes known to be involved in Mtb persistence. Genetic and affinity-based methods identified decaprenyl-phosphoryl-beta-D-ribofuranose oxidoreductase DprE1 and MoeW, enzymes involved in cell wall and molybdenum cofactor biosynthesis, respectively, as targets responsible for the activity of TCA1. These in vitro and in vivo results indicate that this compound functions by a unique mechanism and suggest that TCA1 may lead to the development of a class of antituberculosis agents

DprE1 as a Drug Target from Mycobacterium Tuberculosis

Benzothiazinones (BTZs) form a new class of potent antimycobacterial agents with a minimal inhibitory concentration of 1 ng/mL against Mycobacterium tuberculosis. Although the target of BTZs has been identified as decaprenylphosphoryl--D-ribose 2- oxidase (DprE1), their detailed mechanism of action remains obscure. This thesis provides new insights into BTZ’s mechanism of action demonstrating that these nitroaromatic compounds are activated in the bacterium by reduction of the essential nitro group to a nitroso derivative. This nitroso intermediate then specifically reacts in a near quantitative manner with an active-site cysteine of DprE1, thus providing a rationale for the extraordinary potency of BTZs. Further studies identify DprE1 as the nitroreductase responsible for BTZ activation and classify BTZs as suicide substrates. Mutant DprE1 enzymes from BTZ-resistant strains reduce BTZs to inert metabolites while avoiding covalent inactivation. This work thus provids a detailed picture of the mechanisms of BTZ sensitivity and resistance and represent an important step in the development of BTZs as anti-tuberculosis drugs

Benzothiazinones: prodrugs that covalently modify the decaprenylphosphoryl-β-D-ribose 2'-epimerase DprE1 of Mycobacterium tuberculosis

Benzothiazinones (BTZs) form a new class of potent antimycobacterial agents. Although the target of BTZs has been identified as decaprenylphosphoryl-β-D-ribose 2'-epimerase (DprE1), their detailed mechanism of action remains obscure. Here we demonstrate that BTZs are activated in the bacterium by reduction of an essential nitro group to a nitroso derivative, which then specifically reacts with a cysteine residue in the active site of DprE1

A dual-metal catalyzed sequential cascade reaction in an engineered protein cage

In this study, we describe the creation of an artificial protein cage housing a dual metal-tagged guest protein that catalyzes a linear, two-step sequential cascade reaction. The guest protein consists of a fusion protein of HaloTag and monomeric rhizavidin. Inside the protein capsid, we establish a ruthenium-catalyzed alloc-deprotection followed by a gold-catalyzed ring-closing hydroamination reaction that leads to indoles and phenanthridines with an overall yield of up to 67% in aqueous solutions. Furthermore, we show that the encapsulation stabilizes the metal catalysts against deactivation by air, proteins and cell lysate