title: Characterization and role of the 3-methylglutaconyl coenzyme A hidratase in Trypanosoma brucei.
abstract: Trypanosoma brucei, the agent of African Trypanosomiasis, is a flagellated protozoan parasite that develops in tsetse flies and in the blood of various mammals. The parasite acquires nutrients such as sugars, lipids and amino acids from their hosts. Amino acids are used to generate energy and for protein and lipid synthesis. However, it is still unknown how T. brucei catabolizes most of the acquired amino acids. Here we explored the role of an enzyme of the leucine catabolism, the 3-methylglutaconyl-Coenzyme A hydratase (3-MGCoA-H). It catalyzes the hydration of 3-methylglutaconyl-Coenzyme A (3-MGCoA) into 3-hydroxymethylglutaryl-Coenzyme A (3-HMGCoA). We found that 3-MGCoA-H localizes in the mitochondrial matrix and is expressed in both insect and mammalian bloodstream forms of the parasite. The depletion of 3-MGCoA-H by RNA interference affected minimally the proliferation of both forms. However, an excess of leucine in the culture medium caused growth defects in cells depleted of 3-MGCoA-H, which could be reestablished by mevalonate, a precursor of isoprenoids and steroids. Indeed, procyclics depleted of the 3-MGCoA-H presented reduced levels of synthesized steroids relative to cholesterol that is scavenged by the parasite, and these levels were also reestablished by mevalonate. These results suggest that accumulation of leucine catabolites could affect the level of mevalonate and consequently inhibit the sterol biosynthesis, required for T. brucei growth.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Mariana Leão
authors.initials: ML
authors.lastname: de Lima Stein
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Marcelo Yudi
authors.initials: MY
authors.lastname: Icimoto
authors.affiliation: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Erica Valadares
authors.initials: EV
authors.lastname: de Castro Levatti
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Vitor
authors.initials: V
authors.lastname: Oliveira
authors.affiliation: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Anita Hilda
authors.initials: AH
authors.lastname: Straus
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil. Electronic address: sergioschenkman@gmail.com.
authors.forename: Sergio
authors.initials: S
authors.lastname: Schenkman
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D001711:Biotransformation; D003470:Culture Media / Q000737:chemistry; D020868:Gene Silencing; D006836:Hydro-Lyases / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000254:growth & development*
chemical_list: D000214:Acyl Coenzyme A; D003470:Culture Media; C008047:3-hydroxy-3-methylglutaryl-coenzyme A; D006836:Hydro-Lyases; C035867:methylglutaconyl-CoA hydratase
keywords: 3-methylglutaconyl CoA; Ergosterol; Leucine; Mevalonate; RNAi; Trypanosoma brucei