title: Human hepatitis delta virus RNA subfragments contain an autocleavage activity.
abstract: Hepatitis delta virus (HDV) contains a single-stranded circular RNA genome of 1.7 kilobases. In this report we demonstrate that subfragments of HDV RNA can undergo autocatalytic cleavage. This cleavage requires at least 500 microM of Mg2+ or Ca2+, is not affected by varying the pH from 5.0 to 9.1, and occurs with RNA fragments as small as 133 nucleotides. The larger RNA fragments containing additional HDV sequences have a lower efficiency of cleavage. Deletion analysis at both ends of RNA subfragments suggested that the catalytic ability of HDV RNA resides in a stretch of no more than 117 nucleotides around the cleavage site. The cleavage occurs at the phosphodiester bond between nucleotides 688 and 689 on the HDV genomic map, generating a 5' fragment with a terminal uridyl 2',3'-cyclic monophosphate residue and a 3' fragment with a guanosyl residue with a 5'-hydroxyl group. The smallest autocleaving RNA does not contain the "hammerhead" sequence required for the autocleavage of other known self-cleaving RNA. The cleavage of HDV RNA occurs at a much faster rate, even at a very low Mg2+ concentration, than that of other "ribozymes." Thus, HDV RNA represents a distinct class of ribozyme.
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Republic of China.
authors.forename: H N
authors.initials: HN
authors.lastname: Wu
authors.forename: Y J
authors.initials: YJ
authors.lastname: Lin
authors.forename: F P
authors.initials: FP
authors.lastname: Lin
authors.forename: S
authors.initials: S
authors.lastname: Makino
authors.forename: M F
authors.initials: MF
authors.lastname: Chang
authors.forename: M M
authors.initials: MM
authors.lastname: Lai
mesh_terms: D001483:Base Sequence; D002118:Calcium / Q000494:pharmacology; D003001:Cloning, Molecular; D003698:Hepatitis Delta Virus / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids; D016337:RNA, Catalytic; D012335:RNA, Ribosomal / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D016337:RNA, Catalytic; D012335:RNA, Ribosomal; D012367:RNA, Viral; D008274:Magnesium; D002118:Calcium