title: The esterase and PHD domains in CR1-like non-LTR retrotransposons.
abstract: Most active non-LTR (long terminal repeat) retrotransposons carry two open reading frames (ORFs) encoding ORF1p and ORF2p proteins. The ORF2p proteins are relatively well studied and are known to contain endonuclease/reverse transcriptase domains. At the same time, the biological function of ORF1p proteins remains poorly understood, except in that they nonspecifically bind single-stranded mRNA/DNA molecules. CR1-like elements form the most widely distributed clade/superfamily of non-LTR retrotransposons. We found that ORF1p proteins encoded by diverse CR1-like elements contain conserved esterase domain (ES) or plant homeodomain (PHD). This indicates that CR1-like ORF1p proteins are either lipolytic enzymes or are involved in protein-protein interactions related to chromatin remodeling. Sequence conservation of ES suggests that interaction with cellular membranes is an important phase in life circles of CR1-like elements. Presumably such interaction helps in penetrating host cells. As a consequence, the presence of multiple young CR1 families characterized by approximately 10% intrafamily and 40% interfamily identities may be explained by a relatively frequent horizontal transfer of these CR1-like elements. Unexpectedly, ES links together non-LTR retrotransposons and single-stranded RNA viruses like influenza C and coronaviruses, which are known to depend on their own ES.
authors.affiliation: Genetic Information Research Institute, Mountain View, California, USA.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Kapitonov
authors.forename: Jerzy
authors.initials: J
authors.lastname: Jurka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila / Q000235:genetics; D004950:Esterases / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009990:Oryzias / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D018626:Retroelements / Q000235:genetics*; D016415:Sequence Alignment; D020079:Terminal Repeat Sequences / Q000235:genetics*; D014200:Trematoda / Q000235:genetics; D015027:Zebrafish / Q000235:genetics
chemical_list: D018626:Retroelements; D004950:Esterases