title: Cellular and biochemical characterization of two closely related triosephosphate isomerases from Trichomonas vaginalis.
abstract: The glycolytic enzyme triosephosphate isomerase catalyses the isomerization between glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. Here we report that Trichomonas vaginalis contains 2 fully functional tpi genes. Both genes are located in separated chromosomal context with different promoter regulatory elements and encode ORFs of 254 amino acids; the only differences between them are the character of 4 amino acids located in α-helices 1, 2 and 8. Semi-quantitative RT-PCR assays showed that tpi2 transcript is approximately 3·3-fold more abundant than tpi1. Using an anti-TvTIM2 polyclonal antibody it was demonstrated that TIM proteins have a cytoplasmic localization and both enzymes are able to complement an Escherichia coli strain carrying a deletion of its endogenous tpi gene. Both TIM proteins assemble as dimers and their secondary structure assessment is essentially identical to TIM from Saccharomyces cerevisiae. The kinetic catalytic constants of the recombinant enzymes using glyceraldehyde-3-phosphate as substrate are similar to the catalytic constants of TIMs from other organisms including parasitic protozoa. As T. vaginalis depends on glycolysis for ATP production, we speculate 2 possible reasons to maintain a duplicated tpi copy on its genome: an increase in gene dosage or an early event of neofunctionalization of TIM as a moonlighting protein.
authors.affiliation: Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Col. San Pedro Zacatenco Av. IPN 2508, México, D.F.
authors.forename: Elisa E
authors.initials: EE
authors.lastname: Figueroa-Angulo
authors.forename: Priscila
authors.initials: P
authors.lastname: Estrella-Hernández
authors.forename: Holjes
authors.initials: H
authors.lastname: Salgado-Lugo
authors.forename: Adrián
authors.initials: A
authors.lastname: Ochoa-Leyva
authors.forename: Armando
authors.initials: A
authors.lastname: Gómez Puyou
authors.forename: Silvia S
authors.initials: SS
authors.lastname: Campos
authors.forename: Gabriela
authors.initials: G
authors.lastname: Montero-Moran
authors.forename: Jaime
authors.initials: J
authors.lastname: Ortega-López
authors.forename: Gloria
authors.initials: G
authors.lastname: Saab-Rincón
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.forename: Claudia G
authors.initials: CG
authors.lastname: Benítez-Cardoza
authors.forename: Luis G
authors.initials: LG
authors.lastname: Brieba
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003593:Cytoplasm / Q000201:enzymology; D004926:Escherichia coli / Q000235:genetics; D020440:Gene Duplication; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D005816:Genetic Complementation Test; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D014246:Trichomonas vaginalis / Q000201:enzymology* / Q000235:genetics*; D014305:Triose-Phosphate Isomerase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D014305:Triose-Phosphate Isomerase