SIGI: score-based identification of genomic islands

Background: Genomic islands can be observed in many microbial genomes. These stretches of DNA have a conspicuous composition with regard to sequence or encoded functions. Genomic islands are assumed to be frequently acquired via horizontal gene transfer. For the analysis of genome structure and the study of horizontal gene transfer, it is necessary to reliably identify and characterize these islands. Results: A scoring scheme on codon frequencies Score_G1G2(cdn) = log(f_G2(cdn) / f_G1(cdn)) was utilized. To analyse genes of a species G1 and to test their relatedness to species G2, scores were determined by applying the formula to log-odds derived from mean codon frequencies of the two genomes. A non-redundant set of nearly 400 codon usage tables comprising microbial species was derived; its members were used alternatively at position G2. Genes having at least one score value above a species-specific and dynamically determined cut-off value were analysed further. By means of cluster an...

• Type: Journal
• Year: 2004
• Where: BMCBI
• Authors: Rainer Merkl
• Keywords: BMCBI 2004, Codon Frequencies, Genomic Island, Horizontal Gene Transfer