title: The stability of G6PD is affected by mutations with different clinical phenotypes.
abstract: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme deficiency worldwide, causing a wide spectrum of conditions with severity classified from the mildest (Class IV) to the most severe (Class I). To correlate mutation sites in the G6PD with the resulting phenotypes, we studied four naturally occurring G6PD variants: Yucatan, Nashville, Valladolid and Mexico City. For this purpose, we developed a successful over-expression method that constitutes an easier and more precise method for obtaining and characterizing these enzymes. The k(cat) (catalytic constant) of all the studied variants was lower than in the wild-type. The structural rigidity might be the cause and the most evident consequence of the mutations is their impact on protein stability and folding, as can be observed from the protein yield, the T50 (temperature where 50% of its original activity is retained) values, and differences on hydrophobic regions. The mutations corresponding to more severe phenotypes are related to the structural NADP+ region. This was clearly observed for the Classes III and II variants, which became more thermostable with increasing NADP+, whereas the Class I variants remained thermolabile. The mutations produce repulsive electric charges that, in the case of the Yucatan variant, promote increased disorder of the C-terminus and consequently affect the binding of NADP+, leading to enzyme instability.
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. saulmanzo@ciencias.unam.mx.
authors.forename: Saúl
authors.initials: S
authors.lastname: Gómez-Manzo
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. yssterron@hotmail.com.
authors.forename: Jessica
authors.initials: J
authors.lastname: Terrón-Hernández
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. ignaciodelamora@yahoo.com.mx.
authors.forename: Ignacio
authors.initials: I
authors.lastname: De la Mora-De la Mora
authors.affiliation: Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico. abigaila@correo.biomedicas.unam.mx.
authors.forename: Abigail
authors.initials: A
authors.lastname: González-Valdez
authors.affiliation: CONACyT, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. jmarcialqu@conacyt.mx.
authors.forename: Jaime
authors.initials: J
authors.lastname: Marcial-Quino
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. itzheltorres@hotmail.com.
authors.forename: Itzhel
authors.initials: I
authors.lastname: García-Torres
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. america_vc@yahoo.com.mx.
authors.forename: America
authors.initials: A
authors.lastname: Vanoye-Carlo
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. glv_1999@yahoo.com.
authors.forename: Gabriel
authors.initials: G
authors.lastname: López-Velázquez
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico. galcantara72@yahoo.com.mx.
authors.forename: Gloria
authors.initials: G
authors.lastname: Hernández-Alcántara
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. joria@bq.unam.mx.
authors.forename: Jesús
authors.initials: J
authors.lastname: Oria-Hernández
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. hreyesvivas@yahoo.com.mx.
authors.forename: Horacio
authors.initials: H
authors.lastname: Reyes-Vivas
authors.affiliation: Laboratorio de Bioquímica Genética, Instituto Nacional de Pediatría, México D.F. 04530, Mexico. sergioenr@gmail.com.
authors.forename: Sergio
authors.initials: S
authors.lastname: Enríquez-Flores
mesh_terms: D004795:Enzyme Stability; D005954:Glucosephosphate Dehydrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000201:enzymology* / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D010641:Phenotype; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; D005954:Glucosephosphate Dehydrogenase