Respiratory flexibility in response to inhibition of cytochrome C oxidase in Mycobacterium tuberculosis.
Antimicrob Agents Chemother. 2014 Aug 25;
Authors: Arora K, Ochoa-Montaño B, Tsang PS, Blundell TL, Dawes SS, Mizrahi V, Bayliss T, Mackenzie CJ, Cleghorn LA, Ray PC, Wyatt PG, Uh E, Lee J, Barry CE, Boshoff HI
We report here on a series of five chemically diverse scaffolds that have activity in vitro on both replicating and hypoxic non-replicating bacilli by targeting the respiratory bc1 complex in Mycobacterium tuberculosis, in a strain-dependent manner. Deletion of the cytochrome bd oxidase generated a hyper-susceptible mutant in which resistance was acquired by mutation in qcrB. These results highlight the promiscuity of the bc1 complex and highlight the risk of targeting energy metabolism with new drugs.
PMID: 25155596 [PubMed - as supplied by publisher]
Mycobacterium tuberculosis dihydrofolate reductase reveals two conformational states and a possible low affinity mechanism to antifolate drugs.
Structure. 2014 Jan 7;22(1):94-103
Authors: Dias MV, Tyrakis P, Domingues RR, Paes Leme AF, Blundell TL
Inhibition of the biosynthesis of tetrahydrofolate (THF) has long been a focus in the treatment of both cancer and infectious diseases. Dihydrofolate reductase (DHFR), which catalyzes the last step, is one of the most thoroughly explored targets of this pathway, but there are no DHFR inhibitors used for tuberculosis treatment. Here, we report a structural, site-directed mutagenesis and calorimetric analysis of Mycobacterium tuberculosis DHFR (MtDHFR) in complex with classical DHFR inhibitors. Our study provides insights into the weak inhibition of MtDHFR by trimethoprim and other antifolate drugs, such as pyrimethamine and cycloguanil. The construction of the mutant Y100F, together with calorimetric studies, gives insights into low affinity of MtDHFR for classical DHFR inhibitors. Finally, the structures of MtDHFR in complex with pyrimethamine and cycloguanil define important interactions in the active site and provide clues to the more effective design of antibiotics targeted against MtDHFR.
PMID: 24210757 [PubMed - indexed for MEDLINE]
Pantothenic acid biosynthesis in the parasite Toxoplasma gondii: a target for chemotherapy.
Antimicrob Agents Chemother. 2014 Jul 21;
Authors: Mageed SN, Cunningham F, Hung AW, Silvestre HL, Wen S, Blundell TL, Abell C, McConkey GA
Toxoplasma gondii is a major food pathogen and neglected parasitic infection that causes eye disease, birth defects, and fetal abortion and plays a role as an opportunistic infection in AIDS. In this study, we investigated pantothenic acid (vitamin B5) biosynthesis in T. gondii. Genes encoding the full repertoire of enzymes for pantothenate synthesis and subsequent metabolism to Coenzyme A were identified and are expressed in T. gondii. A panel of inhibitors developed to target Mycobacterium tuberculosis pantothenate synthetase were tested and found to exhibit a range of inhibitions of growth of T. gondii. Two inhibitors exhibited lower effective concentrations than the current toxoplasmosis drug pyrimethamine. The inhibition was specific for the pantothenate pathway as the effect of the pantothenate synthetase inhibitors was abrogated by supplementation with pantothenate. Hence, T. gondii encodes and expresses the enzymes for pantothenate synthesis and this pathway is essential for parasite growth. These promising findings increase our understanding of growth and metabolism in this important parasite and highlight pantothenate synthetase as a new drug target.
PMID: 25049241 [PubMed - as supplied by publisher]
An integrated computational approach can classify VHL missense mutations according to risk of clear cell Renal carcinoma.
Hum Mol Genet. 2014 Jun 26;
Authors: Gossage L, Pires DE, Olivera-Nappa A, Asenjo J, Bycroft M, Blundell TL, Eisen T
Mutations in the von Hippel-Lindau (VHL) gene are pathogenic in VHL disease, congenital polycythaemia and clear cell renal carcinoma. pVHL forms a ternary complex with Elongin C and Elongin B, critical for pVHL stability and function, which interacts with Cullin-2 and RING-box protein 1 to target Hypoxia-inducible factor for polyubiquitination and proteasomal degradation. We describe a comprehensive database of missense VHL mutations linked to experimental and clinical data. We use predictions from in silico tools to link the functional effects of missense VHL mutations to phenotype. The risk of clear cell renal carcinoma in VHL disease is linked to the degree of destabilisation resulting from missense mutations. An optimised binary classification system (Symphony), which integrates predictions from five in silico methods, can predict the risk of ccRCC associated with VHL missense mutations with high sensitivity and specificity. We use Symphony to generate predictions for risk of ccRCC for all possible VHL missense mutations and present these predictions, in association with clinical and experimental data, in a publically available, searchable web server.
PMID: 24969085 [PubMed - as supplied by publisher]