Disease relevance of pO157p22

• They include the 21,000 dalton recombinase (Hin), a 12,000 dalton host protein (Factor II), and one of the major histone-like proteins of E. coli HU [1].
• Bacteriophage P1 encodes its own site-specific recombination system consisting of a site at which recombination takes place called loxP and a recombinase called Cre [2].
• The predicted XisF protein shows significant similarity to the Bacillus subtilis SpoIVCA recombinase [3].
• The Hin recombinase of Salmonella normally catalyzes a site-specific DNA inversion reaction that is very efficient when the Fis protein and a recombinational enhancer sequence are present [4].
• Helper viruses were constructed with packaging signals flanked by loxP sites so that in 293 cells that stably express the Cre recombinase (293Cre), the packaging signal was efficiently excised, rendering the helper virus genome unpackageable [5].

High impact information on pO157p22

• During lambda integration, Int recombinase must specifically bind to and cut attachment sites on both the viral and host chromosomes [6].
• During site-specific DNA recombination, which brings about genetic rearrangement in processes such as viral integration and excision and chromosomal segregation, recombinase enzymes recognize specific DNA sequences and catalyse the reciprocal exchange of DNA strands between these sites [7].
• The data support a model in which C-terminal intersubunit interactions contribute to coupled protein-DNA conformational changes that lead to sequential activation and reciprocal inhibition of pairs of active sites in the recombinase tetramer during recombination [8].
• Recombination reactions using XerC and XerD derivatives that are mutant in their presumptive catalytic residues, or are maltose-binding fusion recombinase derivatives, have demonstrated that this pair of strand exchanges is catalysed by XerC [9].
• This unique association between the integrase-like TnpI recombinase and the TnpA transposase qualifies Tn4430 as a member of a new group within the class II mobile genetic elements [10].

Chemical compound and disease context of pO157p22

• Embryonic stem cells expressing a reporter plasmid that codes for neomycin phosphotransferase and Escherichia coli LacZ were infected with a retroviral gene trap vector (U3Cre) carrying coding sequences for Cre recombinase (Cre) in the U3 region [11].
• The tyrosine at position 60 of the Flp recombinase of the Saccharomyces cerevisiae plasmid, 2 mu circle, is invariant among site-specific recombinases of the "yeast plasmid family". Alterations of this residue give rise to Flp variants that show no recombination activity when assayed in vivo in Escherichia coli [12].
• Oligodeoxynucleotides (ODNs) were conjugated to chlorambucil and used as affinity labeling reagents to study joint molecule formation by the Escherichia coli recombinase recA [13].
• In Escherichia coli, the response to cisplatin involves the action of the prototypic recombinase RecA [14].
• This prophage encodes important functional genes such as lit (T4 exclusion), mcrA (modified cytosine restriction activity) and pin (recombinase) [15].

Biological context of pO157p22

• The endogenous 2 mu plasmid of yeast encodes a site-specific recombinase FLP that can cause an amplification of plasmid copy number [16].
• To this end, a somatic mosaic approach has been developed for the mouse whereby a dormant germline transgene is activated by the somatic delivery and expression of cre recombinase [17].
• Improved properties of FLP recombinase evolved by cycling mutagenesis [18].
• Nerve growth factor somatic mosaicism produced by herpes virus-directed expression of cre recombinase [17].
• Here, we show that the sequence recognition and the catalysis functions of a recombinase can be specified by unrelated protein domains [19].

Anatomical context of pO157p22

• Plasmid DNA containing the M3R ORF with the correct orientation was transfected into Flp-In Chinese hamster ovary (CHO) cells using Flp recombinase-mediated site-specific recombination [20].
• Plastid marker-gene excision by transiently expressed CRE recombinase [21].
• (iii) The BAC vector sequence was almost perfectly excisable from the genome of the reconstituted virus YK304 by coinfection of Vero cells with YK304 and a recombinant adenovirus, AxCANCre, expressing Cre recombinase [22].
• Transgenic lines carrying the WAPiCre PAC express Cre recombinase efficiently in the majority of mammary epithelial cells upon lactation [23].
• The Cre recombinase of bacteriophage P1 catalyses site-specific recombination between lox-recombination target sites both in prokaryotic and eukaryotic cells and has thus become a popular tool in genetic research [24].

Associations of pO157p22 with chemical compounds

• The arginine residue at position 308 in the Flp recombinase corresponds to the only invariant arginine within the Int family of recombinases [25].
• Changing Leu-43 to lysine abolishes the NaeI endonuclease activity and replaces it with topoisomerase and recombinase activities [26].
• The switch lies immediately downstream from the fimE gene, coding for a tyrosine site-specific recombinase that catalyses inversion of the switch from the ON to the OFF phase [27].
• This effect is seen only when phosphorothioate is positioned at a point of potential cleavage by Int recombinase, demonstrating that the inhibition of strand exchange is highly specific [28].
• The positions and characteristics of the mutations support a mechanism for strand exchange by serine recombinases in which the DNA is on the outside of a recombinase tetramer, and the tertiary/quaternary structure of the tetramer is reconfigured [29].

Other interactions of pO157p22

• NaeI, a novel DNA endonuclease, shows topoisomerase and recombinase activities when a Lys residue is substituted for Leu 43 [30].
• Like its parent, the resulting plasmid, pAW800, undergoes complex multiple DNA inversions: this DNA inversion system is therefore called Min. The min gene, which codes for the p15B Min DNA invertase, can complement the P1 cin recombinase gene [31].
• Complementation tests have indicated that both the 5'-->3' exonuclease and the polymerization activities of DNA polymerase I are essential for viability in the absence of RecA protein, whereas the viability and DNA replication of DNA polymerase I-defective cells depend on the recombinase activity of RecA [32].

Analytical, diagnostic and therapeutic context of pO157p22

• Somatic delivery of virus vectors expressing cre recombinase into the brain of NGF-XAT mice resulted in regional recombination and activation of the transgene as demonstrated at the DNA level by PCR and at the protein level by both immunocytochemistry and ELISA [17].
• Directed molecular evolution was applied to generate Cre recombinase variants that recognize a new DNA target sequence [33].
• Site-directed mutagenesis was then used to alter bases implicated in recombinase binding [34].
• We bacterially produced a Cre recombinase containing a nuclear localisation signal as a fusion protein with the E. coli maltose binding protein (MBP) and purified the protein by one step affinity chromatography [24].
• Thus, our system, which is based on transient expression of the Cre recombinase gene directly introduced into nuclei of embryonic cells by microinjection, is a powerful means for cell lineage analysis in mammals [35].

References