title: Consequences of two naturally occurring missense mutations in the structure and function of Bruton agammaglobulinemia tyrosine kinase.
abstract: Bruton agammaglobulinemia tyrosine kinase (BTK) is a key protein in the B-cell receptor (BCR) signaling pathway and plays an essential role in the differentiation of B lymphocytes. X-linked agammaglobulinemia (XLA) is a primary humoral immunodeficiency caused by mutations in the gene encoding BTK. Previously, we identified two novel variations, L111P and E605G, in BTK; these are localized within the pleckstrin homology and Src homology 1 domains, respectively. In the present study, we evaluated the potential effects of these variations on the structural conformation and the function of BTK. Using in silico methods, we found that the L111P and E650G variations are not located directly in protein-protein interfaces but close to them. They distorted the native structural conformation of the BTK protein, affecting not only its geometry and stability but also its ability for protein recognition and in consequence its functionality. To confirm the results of the in silico assays, WT BTK, L111P, and E650G variants were expressed in the BTK-deficient DT40 cell line. The mutant proteins exhibited an absence of catalytic activity, aberrant redistribution after BCR-crosslinking, and deficient intracellular calcium mobilization. This work demonstrates that L111 and E605 residues are fundamental for the activation and function of BTK.
authors.affiliation: Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados-IPN, México, DF, México.
authors.forename: Alexander
authors.initials: A
authors.lastname: Vargas-Hernández
authors.forename: Gabriela
authors.initials: G
authors.lastname: López-Herrera
authors.forename: José L
authors.initials: JL
authors.lastname: Maravillas-Montero
authors.forename: Felipe
authors.initials: F
authors.lastname: Vences-Catalán
authors.forename: Dolores
authors.initials: D
authors.lastname: Mogica-Martínez
authors.forename: Arturo
authors.initials: A
authors.lastname: Rojo-Domínguez
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Espinosa-Rosales
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Santos-Argumedo
mesh_terms: D000293:Adolescent; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000361:Agammaglobulinemia / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D004795:Enzyme Stability; D056726:Genetic Association Studies; D040181:Genetic Diseases, X-Linked / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D006801:Humans; D008297:Male; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D050505:Mutant Proteins; D011947:Receptors, Antigen, B-Cell; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human