Detection and variability analyses of CRISPR-like loci in the H. pylori genome

Abstract

Helicobacter pylori is a human pathogenic bacterium with a high genomic plasticity. Although the functional CRISPR-Cas system has not been found in its genome, CRISPR like loci have been recently identified. In this work, 53 genomes from different geographical areas are analyzed for the search and analysis of variability of this type of structure. We confirm the presence of a locus that was previously described in the VlpC gene in al lgenomes, and we characterize new CRISPR-like loci in other genomic locations. By studying the variability and gene location of these loci, the evolution and the possible roles of these sequences are discussed. Additionally, the usefulness of this type of sequences as a phylogenetic marker has been demonstrated, associating the different strains by geographical area.

Protein-Coding Genes of Helicobacter pylori Predominantly Present Purifying Selection though Many Membrane Proteins Suffer from Selection Pressure: A Proposal to Analyze Bacterial Pangenomes

“…Furthermore, some of these defense systems could be genes involved in CRISPR-Cas systems. Though the presence of this kind of acquired immunity systems is questioned in H. pylori [ 31 , 32 ], two of the proteins found in the accessory group were annotated as CRISPR-associated proteins (the singleton unknown271 , and mjaIM that was found in 65 strains and duplicated in some of them; Supplementary Table S2 ). The cloud group, which includes accessory genes appearing in at least 36 strains, was enriched in regulation as expected, but also in cell division, response to antibiotic, and vesicle-mediated transport.…”

Evaluación de la actividad antimicrobiana de extractos del género Passiflora y búsqueda de bacteriófagos con actividad lítica frente a Helicobacter pylori

“…10 2 CFU con el Hpφ y 10 1 CFU con Hpφ+LF+HA cuando se trataron 24 horas post-infección; en cuanto a la actividad anti-inflamatoria se evidenció disminución en la expresión relativa de los genes TNF-α e IFN-β [38]. Esto es un avance importante en el conocimiento de la interacción entre fagos y H. pylori; sin embargo, teniendo en cuenta que la literatura aún es limitada, se requieren más estudios para tener una mejor comprensión de las interacciones fagohospedero, basados en la presencia de porinas (HopA, HopB, HopC, HopD y HopE), lipopolisacáridos (cadena O-específica que imitan los antígenos del grupo sanguíneo Lewis) y vaina flagelar (compuesta por proteínas y LPS similares a los componentes de la membrana externa) en H. pylori [1], que posiblemente pueden interactuar con las Proteínas de unión a receptores (RBP) de los bacteriófagos en la adsorción [193]; evaluar el ciclo de infección reproductivo, posibles mecanismos de resistencia a la infección, dentro de los que pueden estar involucrados la presencia de profagos en H. pylori [195,196,197,198,199,200,204] o presencia de sistema CRISPR-cas; aunque en H. pylori no se ha encontrado un sistema funcional, solo se han identificado loci semejantes a CRISPR en el gen similar a VacA (VlpC) [205,206].…”