title: Accuracy and efficiency define Bxb1 integrase as the best of fifteen candidate serine recombinases for the integration of DNA into the human genome.
abstract: BACKGROUND
  Phage-encoded serine integrases, such as φC31 integrase, are widely used for genome engineering. Fifteen such integrases have been described but their utility for genome engineering has not been compared in uniform assays.
  
  
  RESULTS
  We have compared fifteen serine integrases for their utility for DNA manipulations in mammalian cells after first demonstrating that all were functional in E. coli. Chromosomal recombination reporters were used to show that seven integrases were active on chromosomally integrated DNA in human fibroblasts and mouse embryonic stem cells. Five of the remaining eight enzymes were active on extra-chromosomal substrates thereby demonstrating that the ability to mediate extra-chromosomal recombination is no guide to ability to mediate site-specific recombination on integrated DNA. All the integrases that were active on integrated DNA also promoted DNA integration reactions that were not mediated through conservative site-specific recombination or damaged the recombination sites but the extent of these aberrant reactions varied over at least an order of magnitude. Bxb1 integrase yielded approximately two-fold more recombinants and displayed about two fold less damage to the recombination sites than the next best recombinase; φC31 integrase.
  
  
  CONCLUSIONS
  We conclude that the Bxb1 and φC31 integrases are the reagents of choice for genome engineering in vertebrate cells and that DNA damage repair is a major limitation upon the utility of this class of site-specific recombinase.
authors.forename: Zhengyao
authors.initials: Z
authors.lastname: Xu
authors.forename: Louise
authors.initials: L
authors.lastname: Thomas
authors.forename: Ben
authors.initials: B
authors.lastname: Davies
authors.forename: Ronald
authors.initials: R
authors.lastname: Chalmers
authors.forename: Maggie
authors.initials: M
authors.lastname: Smith
authors.affiliation: Queens Medical Centre, School of Life Sciences, Nottingham University, Nottingham NG7 2UH, UK. william.brown@nottingham.ac.uk.
authors.forename: William
authors.initials: W
authors.lastname: Brown
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001287:Attachment Sites, Microbiological / Q000235:genetics; D001435:Bacteriophages / Q000201:enzymology / Q000235:genetics; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004254:DNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005354:Fibrosarcoma / Q000378:metabolism; D017353:Gene Deletion; D015894:Genome, Human; D006801:Humans; D019426:Integrases / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D045522:Recombinases / Q000235:genetics* / Q000378:metabolism; D011995:Recombination, Genetic; D012694:Serine / Q000235:genetics* / Q000378:metabolism
chemical_list: D045522:Recombinases; D012694:Serine; D004247:DNA; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C077570:Site-specific recombinase