The Structural Basis of Cryptosporidium-Specific IMP Dehydrogenase Inhibitor Selectivity

Abstract

Cryptosporidium parvum is a potential biowarfare agent, an important AIDS pathogen, and a major cause of diarrhea and malnutrition. No vaccines or effective drug treatment exist to combat Cryptosporidium infection. This parasite relies on inosine 5'-monophosphate dehydrogenase (IMPDH) to obtain guanine nucleotides, and inhibition of this enzyme blocks parasite proliferation. Here, we report the first crystal structures of CpIMPDH. These structures reveal the structural basis of inhibitor selectivity and suggest a strategy for further optimization. Using this information, we have synthesized low-nanomolar inhibitors that display 10(3) selectivity for the parasite enzyme over human IMPDH2.

Identification of novel diphenyl urea inhibitors of Mt-GuaB2 active against Mycobacterium tuberculosis

“…Resistance of M. smegmatis to isoniazid and rifampicin has also been attributed to drug efflux mechanisms (Chaturvedi et al, 2007;Li et al, 2004;Piddock et al, 2000). Remarkably, these DPU inhibitors of Mt-GuaB2 have mechanistic and structural precedent in several compounds identified through high-throughput screening of Cryptosporidium parvum IMPDH (Macpherson et al, 2010). Despite the protozoan nature of C. parvum, its IMPDH has long been thought to have been acquired via gene transfer from a bacterial source (Striepen et al, 2002;Umejiego et al, 2004).…”

2-(Quinolin-4-yloxy)acetamides Are Active against Drug-Susceptible and Drug-Resistant Mycobacterium tuberculosis Strains

“…11 First, the 2-bromo-N-arylacetamides 4a−o and 4q−t were prepared by the acylation reaction of substituted anilines or 1(2)-naphthylamine using bromoacetyl chloride in the presence of 4-dimethyl aminopyridine (DMAP) as a catalyst, according to a previously described protocol. 12,13 Subsequently, 2-(quinolin-4-yloxy)acetamides 2, 5a−o, and 5q−t were synthesized by the O-alkylation reaction of 4-hydroxyquinolines 3a−b with 2-bromo-N-arylacetamides 4a−o and 4q−t in the presence of potassium carbonate using N,N-dimethylformamide (DMF) as the solvent (Scheme 1). The reaction mixtures were stirred for 16 h at 25°C to afford the products with 32−98% yields.…”

Kinetically Controlled Drug Resistance

“…Briefly, plasmids were expressed in a ⌬guaB derivative of E. coli BL21(DE3) (12); purified using a HisTrap affinity column (GE Healthcare) on an Ä KTApurifier TM system (GE Healthcare); and dialyzed into buffer containing 50 mM Tris (pH 8.0), 100 mM KCl, 1 mM DTT, and 10% (v/v) glycerol. All enzymes were purified to Ͼ90% purity as determined by SDS-PAGE.…”