title: Identification of an hepatitis delta virus-like ribozyme at the mRNA 5'-end of the L1Tc retrotransposon from Trypanosoma cruzi.
abstract: L1Tc is a non-LTR LINE element from Trypanosoma cruzi that encodes its transposition machinery and bears an internal promoter. Herewith, we report the identification of an in vitro active hepatitis delta virus-like ribozyme located in the first 77 nt at the 5'-end of the L1Tc mRNA (L1TcRz). The data presented show that L1TcRz has a co-transcriptional function. Using gel-purified uncleaved RNA transcripts, the data presented indicate that the kinetics of the self-cleaving, in a magnesium-dependent reaction, fits to a two-phase decay curve. The cleavage point identified by primer extension takes place at +1 position of the element. The hydroxyl nature of the 5'-end of the 3'-fragment generated by the cleavage activity of L1TcRz was confirmed. Since we have previously described that the 77-nt long fragment located at the 5'-end of L1Tc has promoter activity, the existence of a ribozyme in L1Tc makes this element to be the first described non-LTR retroelement that has an internal promoter-ribozyme dual function. The L1Tc nucleotides located downstream of the ribozyme catalytic motif appear to inhibit its activity. This inhibition may be influenced by the existence of a specific L1Tc RNA conformation that is recognized by RNase P.
authors: Departamento de Biología Molecular, Instituto de Parasitología y Biomedicina López Neyra-CSIC, Parque Tecnológico de Ciencias de Salud, Granada.
authors: Francisco J
authors: FJ
authors: Sánchez-Luque
authors: Manuel C
authors: MC
authors: López
authors: Francisco
authors: F
authors: Macias
authors: Carlos
authors: C
authors: Alonso
authors: M Carmen
authors: MC
authors: Thomas
mesh_terms: D020121:5' Untranslated Regions; D001483:Base Sequence; D020134:Catalytic Domain; D003698:Hepatitis Delta Virus / Q000201:enzymology; D007700:Kinetics; D020084:Long Interspersed Nucleotide Elements; D008969:Molecular Sequence Data; D059367:RNA Cleavage; D059370:RNA Folding; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry*; D043262:Ribonuclease P / Q000378:metabolism; D014158:Transcription, Genetic; D014349:Trypanosoma cruzi / Q000235:genetics*
chemical_list: D020121:5' Untranslated Regions; D016337:RNA, Catalytic; D012333:RNA, Messenger; D043262:Ribonuclease P