Evolution of the structural repertoire of the human V(H) and V(?) germline genes
Por:
Vargas-Madrazo E., Lara-Ochoa F., Ramirez-Benites M.C., Almagro J.C.
Publicada:
1 ene 1997
Resumen:
Variable genes of human Ig are classified in families and clans which reflect the early events of gene duplication in the evolution of the locus. This organization in multiple copies of variable genes plus the somatic processes of recombination and hypermutation allows the immune system to generate an antibody repertoire of great diversity. At present the role that somatic processes play in the generation of that diversity is understood with some detail. It is a matter of hard controversy, however, which selective pressures have shaped the evolution of the germline genes of Ig and, consequently, what the role of this germline component in the generation of the antibody diversity actually is. Previous studies of our group have showed that the structural repertoire of Ig - determined by the canonical structures - is an important factor to determine the recognition properties of the antibodies. Complete knowledge of the sequences of the human V(H) and V? loci is available to analyze the evolution of the structural repertoire of these loci. Two phylogenetic gene trees were built from the functional germline genes and the evolution of the structural repertoire was studied. We report that for both loci the canonical structures are not randomly distributed within the tree. Conversely, it is shown that the evolution of the structural repertoire follows a gradual process of diversification. This indicates a correlation between the evolution of genes and the structural repertoire, although important differences are found in the patterns of evolution of the structural repertoire between V(H) and V?. Based on those results we propose a primordial structural repertoire for V(H) and V?. The general properties and an outline of the three-dimensional structure of this primordial repertoire are given.
Filiaciones:
Vargas-Madrazo E.:
Inst. de Invest. Biológicas, Universidad Veracruzana, Apartado Postal 495, Xalapa, Veracruz 91000, Mexico
Lara-Ochoa F.:
Instituto de Química, Univ. Nac. Auton. de México, Ciudad Universitaria, CP 04510, México, DF, Mexico
Ramirez-Benites M.C.:
Inst. de Invest. Biológicas, Universidad Veracruzana, Apartado Postal 495, Xalapa, Veracruz 91000, Mexico
Almagro J.C.:
Instituto de Química, Univ. Nac. Auton. de México, Ciudad Universitaria, CP 04510, México, DF, Mexico
Bronze
|