title: Substrate-Induced Dimerization of Engineered Monomeric Variants of Triosephosphate Isomerase from Trichomonas vaginalis.
abstract: The dimeric nature of triosephosphate isomerases (TIMs) is maintained by an extensive surface area interface of more than 1600 Å2. TIMs from Trichomonas vaginalis (TvTIM) are held in their dimeric state by two mechanisms: a ball and socket interaction of residue 45 of one subunit that fits into the hydrophobic pocket of the complementary subunit and by swapping of loop 3 between subunits. TvTIMs differ from other TIMs in their unfolding energetics. In TvTIMs the energy necessary to unfold a monomer is greater than the energy necessary to dissociate the dimer. Herein we found that the character of residue I45 controls the dimer-monomer equilibrium in TvTIMs. Unfolding experiments employing monomeric and dimeric mutants led us to conclude that dimeric TvTIMs unfold following a four state model denaturation process whereas monomeric TvTIMs follow a three state model. In contrast to other monomeric TIMs, monomeric variants of TvTIM1 are stable and unexpectedly one of them (I45A) is only 29-fold less active than wild-type TvTIM1. The high enzymatic activity of monomeric TvTIMs contrast with the marginal catalytic activity of diverse monomeric TIMs variants. The stability of the monomeric variants of TvTIM1 and the use of cross-linking and analytical ultracentrifugation experiments permit us to understand the differences between the catalytic activities of TvTIMs and other marginally active monomeric TIMs. As TvTIMs do not unfold upon dimer dissociation, herein we found that the high enzymatic activity of monomeric TvTIM variants is explained by the formation of catalytic dimeric competent species assisted by substrate binding.
authors.affiliation: IPICYT, División de Biología Molecular, Camino a la Presa San José 2055, CP 78216, San Luis Potosí, San Luis Potosí, México.
authors.forename: Samuel
authors.initials: S
authors.lastname: Lara-Gonzalez
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Estrella
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Carmen
authors.initials: C
authors.lastname: Portillo
authors.affiliation: Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-IPN, Guillermo Massieu Helguera No. 239, La Escalera Ticoman, 07320, D.F, Mexico.
authors.forename: María E
authors.initials: ME
authors.lastname: Cruces
authors.affiliation: Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-IPN, Guillermo Massieu Helguera No. 239, La Escalera Ticoman, 07320, D.F, Mexico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Jimenez-Sandoval
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais Campinas SP, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Fattori
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais Campinas SP, Brazil.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Migliorini-Figueira
authors.affiliation: Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-IPN, Guillermo Massieu Helguera No. 239, La Escalera Ticoman, 07320, D.F, Mexico.
authors.forename: Marisol
authors.initials: M
authors.lastname: Lopez-Hidalgo
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Corina
authors.initials: C
authors.lastname: Diaz-Quezada
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Margarita
authors.initials: M
authors.lastname: Lopez-Castillo
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Trasviña-Arenas
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Sanchez-Sandoval
authors.affiliation: Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, México.
authors.forename: Armando
authors.initials: A
authors.lastname: Gómez-Puyou
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del IPN, Col. San Pedro Zacatenco, Av. IPN, 2508, C.P. 07360, D.F., México.
authors.forename: Jaime
authors.initials: J
authors.lastname: Ortega-Lopez
authors.affiliation: Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Col. San Pedro Zacatenco, Av. IPN, 2508, C.P. 07360, D.F., México.
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.affiliation: Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-IPN, Guillermo Massieu Helguera No. 239, La Escalera Ticoman, 07320, D.F, Mexico.
authors.forename: Claudia G
authors.initials: CG
authors.lastname: Benítez-Cardoza
authors.affiliation: Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, México.
authors.forename: Luis G
authors.initials: LG
authors.lastname: Brieba
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D011485:Protein Binding; D055503:Protein Multimerization; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D014246:Trichomonas vaginalis / Q000201:enzymology*; D014305:Triose-Phosphate Isomerase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D014305:Triose-Phosphate Isomerase