In Silico Study Of Pathogenicity Islands Of Salmonella Enterica Serovar Typhi

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Date
2011-02
Authors
Ong, Su Yean
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Publisher
Universiti Sains Malaysia
Abstract
Salmonella enterica serovar Typhi is a human-specific pathogen that causes Typhoid Fever. It is reported that 3-5% of infected patients end up as Typhoid Carriers. This bacterium harbors several genomic islands known as Salmonella Pathogenicity Islands (SPIs). The SPIs carry virulence and other genes essential for infection. The objective of this study is to identify the SPI proteins and their interactions in these genomic islands. In parallel, a comparative genomic study for all the SPIs using manual curation and de novo functional assignment was performed in all available completed and draft genomes of S. Typhi strains. For the first time, a thorough, extensive and indepth in silico study was undertaken to identify all SPI proteins and their putative regulation. MedScan information extraction technology and Pathway Studio software were the main tools used for the reconstruction of SPI pathways, while extensive BLAST analysis were applied to analyze the sequences from other S. Typhi strains. In summary, the collection of 17 constructed SPI pathways were shown to be interconnected despite their different location on the genome and all of them played an important role for Typhoid Fever. It was revealed that SPI-1 is interacting with the largest number of SPIs, namely SPI-2, 3, 4, 5, 7, and 18 through the PhoP/PhoQ system. Several clusters of genes co-expressed during macrophage invasion were identified in the SPI pathways. Based on the comparative studies, it was discovered that most of the key players in the SPIs especially the transcription factors and global regulators, were indeed conserved throughout the Salmonella lineage.
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Keywords
Pathogenicity Islands , Salmonella Enterica Serovar Typhi
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