title: Generation of functional RNAs from inactive oligonucleotide complexes by non-enzymatic primer extension.
abstract: The earliest genomic RNAs had to be short enough for efficient replication, while simultaneously serving as unfolded templates and effective ribozymes. A partial solution to this paradox may lie in the fact that many functional RNAs can self-assemble from multiple fragments. Therefore, in early evolution, genomic RNA fragments could have been significantly shorter than unimolecular functional RNAs. Here, we show that unstable, nonfunctional complexes assembled from even shorter 3'-truncated oligonucleotides can be stabilized and gain function via non-enzymatic primer extension. Such short RNAs could act as good templates due to their minimal length and complex-forming capacity, while their minimal length would facilitate replication by relatively inefficient polymerization reactions. These RNAs could also assemble into nascent functional RNAs and undergo conversion to catalytically active forms, by the same polymerization chemistry used for replication that generated the original short RNAs. Such phenomena could have substantially relaxed requirements for copying efficiency in early nonenzymatic replication systems.
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital , 185 Cambridge Street, Boston, Massachusetts 02114, United States.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Adamala
authors.forename: Aaron E
authors.initials: AE
authors.lastname: Engelhart
authors.forename: Jack W
authors.initials: JW
authors.lastname: Szostak
mesh_terms: D009841:Oligonucleotides / Q000737:chemistry* / Q000378:metabolism*; D058105:Polymerization; D012313:RNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D009841:Oligonucleotides; D016337:RNA, Catalytic; D012313:RNA