title: Differential inhibition of LINE1 and LINE2 retrotransposition by vertebrate AID/APOBEC proteins.
abstract: BACKGROUND
  The role of AID/APOBEC proteins in the mammalian immune response against retroviruses and retrotransposons is well established. G to A hypermutations, the hallmark of their cytidine deaminase activity, are present in several mammalian retrotransposons. However, the role of AID/APOBEC proteins in non-mammalian retroelement restriction is not completely understood.
  
  
  RESULTS
  Here we provide the first evidence of anti-retroelement activity of a reptilian APOBEC protein. The green anole lizard A1 protein displayed potent DNA mutator activity and inhibited ex vivo retrotransposition of LINE1 and LINE2 ORF1 protein encoding elements, displaying a mechanism of action similar to that of the human A1 protein. In contrast, the human A3 proteins did not require ORF1 protein to inhibit LINE retrotransposition, suggesting a differential mechanism of anti-LINE action of A1 proteins, which emerged in amniotes, and A3 proteins, exclusive to placental mammals. In accordance, genomic analyses demonstrate differential G to A DNA editing of LINE retrotransposons in the lizard genome, which is also the first evidence for G to A DNA editing in non-mammalian genomes.
  
  
  CONCLUSIONS
  Our data suggest that vertebrate APOBEC proteins differentially inhibit the retrotransposition of LINE elements and that the anti-retroelement activity of APOBEC proteins predates mammals.
authors.forename: Nataša
authors.initials: N
authors.lastname: Lindič
authors.forename: Maruška
authors.initials: M
authors.lastname: Budič
authors.forename: Toni
authors.initials: T
authors.lastname: Petan
authors.forename: Binyamin A
authors.initials: BA
authors.lastname: Knisbacher
authors.forename: Erez Y
authors.initials: EY
authors.lastname: Levanon
authors.affiliation: Department of Chemistry and Biochemistry, Chair of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000, Ljubljana, Slovenia. nika.lovsin@fkkt.uni-lj.si.
authors.forename: Nika
authors.initials: N
authors.lastname: Lovšin
mesh_terms: D000818:Animals; D003564:Cytidine Deaminase / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D018626:Retroelements / Q000276:immunology*; D014714:Vertebrates / Q000276:immunology*
chemical_list: D018626:Retroelements; D003564:Cytidine Deaminase