title: In vivo characterization of the homing endonuclease within the polB gene in the halophilic archaeon Haloferax volcanii.
abstract: Inteins are parasitic genetic elements, analogous to introns that excise themselves at the protein level by self-splicing, allowing the formation of functional non-disrupted proteins. Many inteins contain a homing endonuclease (HEN) gene, and rely on its activity for horizontal propagation. In the halophilic archaeon, Haloferax volcanii, the gene encoding DNA polymerase B (polB) contains an intein with an annotated but uncharacterized HEN. Here we examine the activity of the polB HEN in vivo, within its natural archaeal host. We show that this HEN is highly active, and able to insert the intein into both a chromosomal target and an extra-chromosomal plasmid target, by gene conversion. We also demonstrate that the frequency of its incorporation depends on the length of the flanking homologous sequences around the target site, reflecting its dependence on the homologous recombination machinery. Although several evolutionary models predict that the presence of an intein involves a change in the fitness of the host organism, our results show that a strain deleted for the intein sequence shows no significant changes in growth rate compared to the wild type.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Adit
authors.initials: A
authors.lastname: Naor
authors.forename: Rona
authors.initials: R
authors.lastname: Lazary
authors.forename: Adi
authors.initials: A
authors.lastname: Barzel
authors.forename: R Thane
authors.initials: RT
authors.lastname: Papke
authors.forename: Uri
authors.initials: U
authors.lastname: Gophna
mesh_terms: D005075:Biological Evolution; D002875:Chromosomes / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004720:Endonucleases / Q000235:genetics*; D005785:Gene Conversion; D056084:Genetic Fitness; D019622:Haloferax volcanii / Q000201:enzymology*; D047668:Inteins / Q000235:genetics; D010957:Plasmids / Q000235:genetics
chemical_list: D004259:DNA-Directed DNA Polymerase; D004720:Endonucleases