title: Group I intron homing in Bacillus phages SPO1 and SP82: a gene conversion event initiated by a nicking homing endonuclease.
abstract: Many group I introns encode endonucleases that promote intron homing by initiating a double-stranded break-mediated homologous recombination event. In this work we describe intron homing in Bacillus subtilis phages SPO1 and SP82. The introns encode the DNA endonucleases I-HmuI and I-HmuII, respectively, which belong to the H-N-H endonuclease family and possess nicking activity in vitro. Coinfections of B. subtilis with intron-minus and intron-plus phages indicate that I-HmuI and I-HmuII are required for homing of the SPO1 and SP82 introns, respectively. The homing process is a gene conversion event that does not require the major B. subtilis recombination pathways, suggesting that the necessary functions are provided by phage-encoded factors. Our results provide the first examples of H-N-H endonuclease-mediated intron homing and the first demonstration of intron homing initiated by a nicking endonuclease.
authors.affiliation: Department of Biological Sciences and Center for Molecular Genetics, University at Albany, State University of New York, Albany, New York 12222, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Landthaler
authors.forename: Nelson C
authors.initials: NC
authors.lastname: Lau
authors.forename: David A
authors.initials: DA
authors.lastname: Shub
mesh_terms: D017103:Bacillus Phages / Q000235:genetics*; D001483:Base Sequence; D003850:Deoxyribonuclease I / Q000502:physiology*; D005785:Gene Conversion; D007438:Introns; D008969:Molecular Sequence Data
chemical_list: D003850:Deoxyribonuclease I