title: Analysis of a genomic island housing genes for DNA S-modification system in Streptomyces lividans 66 and its counterparts in other distantly related bacteria.
abstract: The complete sequence (92 770 bp) of a genomic island (GI) named SLG from Streptomyces lividans 66, encoding a novel DNA S-modification system (dnd), was determined. Its overall G+C content was 67.8%, lower than those of three sequenced Streptomyces genomes. Among 85 predicted open reading frames (ORFs) in SLG, 22 ORFs showed little homology with previously known proteins. SLG displays a mosaic structure composed of four modules, indicative of multiple recombination events in its formation. Spontaneous excision and circularization of SLG was observed, and the excision rate appeared to be induced at least fivefold by MNNG exposure. Using constructed mini-islands of SLG, we demonstrated that Slg01, a P4-like integrase, was sufficient to promote SLG integration, excision and circularization. Eleven counterpart dnd clusters, which also mapped to GIs in 10 chromosomes and a plasmid, were found in taxonomically unrelated bacterial species from various geographic niches. Additionally, c. 10% of actinomycetes were found to possess a dnd cluster in a survey involving 74 strains. Comparison of dnd clusters in the 12 bacteria strongly suggests that these dnd-bearing elements might have evolved from a common ancestor similar to plasmid-originated chromosome II of Pseudoalteromonas haloplanktis TAC125.
authors.affiliation: Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: He
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Ou
authors.forename: Qing
authors.initials: Q
authors.lastname: Yu
authors.forename: Xiufen
authors.initials: X
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.forename: Jingdan
authors.initials: J
authors.lastname: Liang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Kumar
authors.initials: K
authors.lastname: Rajakumar
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
mesh_terms: D001482:Base Composition / Q000235:genetics; D002876:Chromosomes, Bacterial; D016000:Cluster Analysis; D015280:DNA Restriction-Modification Enzymes / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics; D005798:Genes, Bacterial; D044404:Genomic Islands / Q000235:genetics*; D019426:Integrases / Q000378:metabolism; D010802:Phylogeny; D011995:Recombination, Genetic / Q000235:genetics; D017422:Sequence Analysis, DNA; D048170:Streptomyces lividans / Q000235:genetics*; D013379:Substrate Specificity
chemical_list: D015280:DNA Restriction-Modification Enzymes; D004251:DNA Transposable Elements; D019426:Integrases