In silico comparative study of the genomic islands of Vibrio cholerae\ud MJ1236 with those of Classical and El TorN16961 strains of\ud Vibrio cholerae

摘要

The evolution of microbial genomes is greatly influenced by horizontal gene\udtransfer (HGT), where large blocks of horizontally acquired foreign sequences,\udoften encoding virulence determinants, occur in chromosomes of pathogenic\udbacteria. A program DESIGN-ISLAND developed in our laboratory was used on three\udcompletely sequenced Vibrio cholerae genomes, V. cholerae Classical O395, El Tor\udN16961 and MJ1236, in order to identify the putative horizontally acquired\udregions. The putative genomic islands (GIs) were graphically represented and\udanalyzed. The study identified distinct regions in the GIs of V. cholerae MJ1236\udwhich were shared either with the Classical or the El Tor strain of V. cholerae. A\udcluster comprising of 38 ORFs was common to V. cholerae strains of MJ1236 and\udClassical O395 but absent in El Tor N16961. About 5% of the predicted GIs of V.\udcholerae MJ1236 were unique to itself. Among these unique ORFs, a region of\udmostly hypothetical genes was identified, where the ORFs were present in a large\udcluster. The results show that the HGT had played a significant role in the\udevolution and the differentiation of V. cholerae MJ1236.