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Functional characteristics of a highly specific integrase encoded by an LTR-retrotransposon.

ABSTRACT: BACKGROUND: The retroviral Integrase protein catalyzes the insertion of linear viral DNA into host cell DNA. Although different retroviruses have been shown to target distinctive chromosomal regions, few of them display a site-specific integration. ZAM, a retroelement from Drosophila melanogaster very similar in structure and replication cycle to mammalian retroviruses is highly site-specific. Indeed, ZAM copies target the genomic 5'-CGCGCg-3' consensus-sequences. To enlighten the determinants of this high integration specificity, we investigated the functional properties of its integrase protein denoted ZAM-IN. PRINCIPAL FINDINGS: Here we show that ZAM-IN displays the property to nick DNA molecules in vitro. This endonuclease activity targets specific sequences that are present in a 388 bp fragment taken from the white locus and known to be a genomic ZAM integration site in vivo. Furthermore, ZAM-IN displays the unusual property to directly bind specific genomic DNA sequences. Two specific and independent sites are recognized within the 388 bp fragment of the white locus: the CGCGCg sequence and a closely apposed site different in sequence. CONCLUSION: This study strongly argues that the intrinsic properties of ZAM-IN, ie its binding properties and its endonuclease activity, play an important part in ZAM integration specificity. Its ability to select two binding sites and to nick the DNA molecule reminds the strategy used by some site-specific recombination enzymes and forms the basis for site-specific integration strategies potentially useful in a broad range of genetic engineering applications.

SUBMITTER: Faye B

PROVIDER: S-EPMC2527525 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Functional characteristics of a highly specific integrase encoded by an LTR-retrotransposon.

Faye Babacar B Arnaud Frederick F Peyretaillade Eric E Brasset Emilie E Dastugue Bernard B Vaury Chantal C

PloS one 20080911 9

<h4>Background</h4>The retroviral Integrase protein catalyzes the insertion of linear viral DNA into host cell DNA. Although different retroviruses have been shown to target distinctive chromosomal regions, few of them display a site-specific integration. ZAM, a retroelement from Drosophila melanogaster very similar in structure and replication cycle to mammalian retroviruses is highly site-specific. Indeed, ZAM copies target the genomic 5'-CGCGCg-3' consensus-sequences. To enlighten the determi ...[more]

PMID: 18784842

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Project description:Amongst the 11 eutherian-specific genes acquired from a sushi-ichi retrotransposon is the CCHC type zinc-finger protein-encoding gene SIRH11/ZCCHC16. Its contribution to eutherian brain evolution is implied because of its involvement in cognitive function in mice, possibly via the noradrenergic system. Although, the possibility that Sirh11/Zcchc16 functions as a non-coding RNA still remains, dN/dS ratios in pairwise comparisons between its orthologs have provided supportive evidence that it acts as a protein. It became a pseudogene in armadillos (Cingulata) and sloths (Pilosa), the only two extant orders of xenarthra, which prompted us to examine the lineage-specific variations of SIRH11/ZCCHC16 in eutherians. We examined the predicted SIRH11/ZCCHC16 open reading frame (ORF) in 95 eutherian species based on the genomic DNA information in GenBank. A large variation in the SIRH11/ZCCHC16 ORF was detected in several lineages. These include a lack of a CCHC RNA-binding domain in its C-terminus, observed in gibbons (Hylobatidae: Primates) and megabats (Megachiroptera: Chiroptera). A lack of the N-terminal half, on the other hand, was observed in New World monkeys (Platyrrhini: Primates) and species belonging to New World and African Hystricognaths (Caviomorpha and Bathyergidae: Rodents) along with Cetacea and Ruminantia (Cetartiodactyla). Among the hominoids, interestingly, three out of four genera of gibbons have lost normal SIRH11/ZCCHC16 function by deletion or the lack of the CCHC RNA-binding domain. Our extensive dN/dS analysis suggests that such truncated SIRH11/ZCCHC16 ORFs are functionally diversified even within lineages. Combined, our results show that SIRH11/ZCCHC16 may contribute to the diversification of eutherians by lineage-specific structural changes after its domestication in the common eutherian ancestor, followed by putative species-specific functional changes that enhanced fitness and occurred as a consequence of complex natural selection events.

Dataset Information

Functional characteristics of a highly specific integrase encoded by an LTR-retrotransposon.

Publications

Functional characteristics of a highly specific integrase encoded by an LTR-retrotransposon.

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