RESUMEN
The population of India harbors one of the world's most highly diverse gene pools, owing to the influx of successive waves of immigrants over regular periods in time. Several phylogenetic studies involving mitochondrial DNA and Y chromosomal variation have demonstrated Europeans to have been the first settlers in India. Nevertheless, certain controversy exists, due to the support given to the thesis that colonization was by the Austro-Asiatic group, prior to the Europeans. Thus, the aim was to investigate pre-historic colonization of India by anatomically modern humans, using conserved stretches of five amino acid (EPIYA) sequences in the cagA gene of Helicobacter pylori. Simultaneously, the existence of a pathogenic relationship of tyrosine phosphorylation motifs (TPMs), in 32 H. pylori strains isolated from subjects with several forms of gastric diseases, was also explored. High resolution sequence analysis of the above described genes was performed. The nucleotide sequences obtained were translated into amino acids using MEGA (version 4.0) software for EPIYA. An MJ-Network was constructed for obtaining TPM haplotypes by using NETWORK (version 4.5) software. The findings of the study suggest that Indian H. pylori strains share a common ancestry with Europeans. No specific association of haplotypes with the outcome of disease was revealed through additional network analysis of TPMs.
RESUMEN
El gen cagA de Helicobacter pylori codifica para la proteína CagA considerada uno de los factores de virulencia cuya presencia se asocia a un mayor riesgo de padecer enfermedades gástricas severas. El presente estudio planteó como objetivo el diseño de una estrategia molecular y bioinformática útil en la determinación de la presencia de secuencias repetitivas que pueden contener uno o más motivos de fosforilación (EPIYA). Se amplificó y secuenció la región variable de cagA en muestras H. pylori CagA positivas. Se realizó una búsqueda y selección de herramientas bioinformáticas que permitieran establecer las características de los motivos EPIYA. La presencia de motivos tipo EPIYA-A y EPIYA-B, seguido por una a dos repeticiones de EPIYA-C, similares a los reportados para países de Occidente, fueron encontrados. De las aplicaciones bioinformáticas evaluadas, solo un conjunto de herramientas demostró ser útil en la caracterización de las unidades de repetición en la proteína CagA.
Helicobacter pylori CagA protein, the cagA gen product, has been considered as a virulence factor associated with a considerable increase risk for develops severe gastric illness. The purpose of this research was to design a molecular and bioinformatics strategy that allowed the establishment of phosphorylation status of the tyrosine residue of the CagA protein. The amplification and sequencing of the variable fragment region of cagA in the positive CagA samples were used to do the bioinformatics analysis in order to establish the characteristics of the EPIYA motifs. The presence of the EPIYA-A and EPIYA-B motifs, followed by one or two EPIYA-C repetitions, similar to those reported previously for occidental countries were set up. From the different bioinformatics applications that were employed only one group of tools proved to be useful to characterize the repeated units presents in the CagA protein.