Document Detail

Integration specificity of phage phiC31 integrase in the human genome.
MedLine Citation:
PMID:  16414067     Owner:  NLM     Status:  MEDLINE    
The site-specific integrase from bacteriophage phiC31 functions in mammalian cells and is being applied for genetic engineering, including gene therapy. The phiC31 integrase catalyzes precise, unidirectional recombination between its 30-40-bp attP and attB recognition sites. In mammalian cells, the enzyme also mediates integration of plasmids bearing attB into native sequences that have partial sequence identity with attP, termed pseudo attP sites. Here, we analyzed the features of phiC31-mediated integration into pseudo attP sites in the human genome. Sequence analysis of 196 independent integration events derived from three cell lines revealed approximately 101 integration sites: 56% of the events were recurrent integrations distributed among 19 pseudo attP sequences. Bioinformatics analysis revealed a approximately 30-bp palindromic consensus sequence motif shared by all of the repeat occurrences and most of the single occurrence sites, verifying that phiC31-mediated integration into pseudo attP sites is significantly guided by DNA sequence recognition. The most favored unique sequence in these cell lines occurred at chromosome 19q13.31 and accounted for 7.5% of integration events. Other frequent integration sites were in three specific sequences in subfamilies of ERVL and L1 repetitive sequences, accounting for an additional 17.9% of integration events. Integrations could occur in either orientation at a pseudo attP site, were often accompanied by small deletions, and typically occurred in a single copy per cell. A number of aberrant events were also described, including large deletions and chromosome rearrangements. phiC31 integrase-mediated integration only slightly favored genes and did not favor promoter regions. Gene density and expression studies suggested chromatin context effects. An analysis of the safety of integration sites in terms of proximity to cancer genes suggested minimal cancer risk. We conclude that integration systems derived from phiC31 integrase have great potential utility.
Thomas W Chalberg; Joylette L Portlock; Eric C Olivares; Bhaskar Thyagarajan; Patrick J Kirby; Robert T Hillman; Juergen Hoelters; Michele P Calos
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2005-12-22
Journal Detail:
Title:  Journal of molecular biology     Volume:  357     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-03-13     Completed Date:  2006-04-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  28-48     Citation Subset:  IM    
Department of Genetics, Stanford University School of Medicine, Stanford, CA 95305-5120, USA.
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MeSH Terms
Attachment Sites, Microbiological*
Bacteriophages / enzymology*,  genetics
Base Sequence
Cell Line
Chromosomes, Human
Computational Biology
Genome, Human*
In Situ Hybridization, Fluorescence
Integrases / genetics,  metabolism*
Molecular Sequence Data
Recombination, Genetic
Sequence Homology, Nucleic Acid
Grant Support
Reg. No./Substance:
EC 2.7.7.-/Integrases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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