Site promiscuity of coliphage HK022 integrase as a tool for gene therapy

• Published in: Gene therapy 2015-07, Vol.22 (7), p.521-527
• Main Authors: Kolot, M, Malchin, N, Elias, A, Gritsenko, N, Yagil, E
• Format: Article
• Language: English
• Subjects: 45; 45/41; 631/337; 631/337/149; Attachment Sites, Microbiological; Binding sites; Biomedical and Life Sciences; Biomedicine; Cell Biology; Chromosomes; Coliphages - genetics; Coliphages - metabolism; Conserved sequence; Escherichia coli K12; Gene Expression; Gene mutations; Gene Therapy; Genetic recombination; Genetic Therapy; Genome, Human; Genomes; HEK293 Cells; Human Genetics; Humans; Influence; Integrase; Integrases - genetics; Integrases - metabolism; Mutation; Nanotechnology; Nucleotide sequence; original-article; Phages; Promiscuity; Recombinase; Recombination; Recombination, Genetic
• ISSN: 0969-7128; 1476-5462
• DOI: 10.1038/gt.2015.9

The integrase (Int) encoded by the lambdoid coliphage HK022 targets in its host chromosome a 21 base pair (bp) recombination site termed attB or BOB'. attB comprises two 7 bp partially inverted (palindromic) Int-binding sites of 7 bp each termed B and B'. B and B' flank a central 7 bp crossover site or ‘overlap’ (O). We show that replacing O with a random 7 bp sequence supports Int-mediated site-specific recombination as long as the cognate and larger phage recombination site attP features an identical O sequence. This promiscuity allowed us to identify on the human genome several native active secondary attB sites (‘ attB ’) with random overlaps that flank human deleterious mutations, raising the prospect of using such sites to cure the ‘ attB ’-flanked mutations by Int-catalyzed RMCE (recombinase-mediated cassette exchange) reactions. An analysis of such active and inactive ‘ attB ’s suggested a minimal 14–15 bp attB consensus sequence (instead of the 21 bp) with a reduced 3 bp palindrome.