Viroids: the minimal non-coding RNAs with autonomous replication.
Viroids are small (246-401 nucleotides), non-coding, circular RNAs able to replicate autonomously in certain plants. Viroids are classified into the families Pospiviroidae and Avsunviroidae, whose members replicate in the nucleus and chloroplast, respectively. Replication occurs by an RNA-based rolling-circle mechanism in three steps: (1). synthesis of longer-than-unit strands catalyzed by host DNA-dependent RNA polymerases forced to transcribe RNA templates, (2). processing to unit-length, which in family Avsunviroidae is mediated by hammerhead ribozymes, and (3). circularization either through an RNA ligase or autocatalytically. Disease induction might result from the accumulation of viroid-specific small interfering RNAs that, via RNA silencing, could interfere with normal developmental pathways.
Flores
Ricardo
R
Instituto de Biología Molecular y Celular de Plantas (UPV-CSIC), Universidad Politécnica de Valencia, 46022 Valencia, Spain. rflores@ibmcp.upv.es
Delgado
Sonia
S
Gas
María-Eugenia
ME
Carbonell
Alberto
A
Molina
Diego
D
Gago
Selma
S
De la Peña
Marcos
M
D001483:Base Sequence; D004247:DNA / Q000737:chemistry; D020868:Gene Silencing; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010942:Plant Viruses / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*; D034622:RNA Interference; D012323:RNA Processing, Post-Transcriptional; D016337:RNA, Catalytic / Q000737:chemistry; D014772:Viroids / Q000737:chemistry* / Q000502:physiology*; D014779:Virus Replication
D016337:RNA, Catalytic; C427204:hammerhead ribozyme; D012313:RNA; D004247:DNA