A self-replicating ligase ribozyme.
A self-replicating molecule directs the covalent assembly of component molecules to form a product that is of identical composition to the parent. When the newly formed product also is able to direct the assembly of product molecules, the self-replicating system can be termed autocatalytic. A self-replicating system was developed based on a ribozyme that catalyzes the assembly of additional copies of itself through an RNA-catalyzed RNA ligation reaction. The R3C ligase ribozyme was redesigned so that it would ligate two substrates to generate an exact copy of itself, which then would behave in a similar manner. This self-replicating system depends on the catalytic nature of the RNA for the generation of copies. A linear dependence was observed between the initial rate of formation of new copies and the starting concentration of ribozyme, consistent with exponential growth. The autocatalytic rate constant was 0.011 min(-1), whereas the initial rate of reaction in the absence of pre-existing ribozyme was only 3.3 x 10(-11) M.min(-1). Exponential growth was limited, however, because newly formed ribozyme molecules had greater difficulty forming a productive complex with the two substrates. Further optimization of the system may lead to the sustained exponential growth of ribozymes that undergo self-replication.
Paul
Natasha
N
Departments of Chemistry and Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Joyce
Gerald F
GF
D001483:Base Sequence; D001669:Biochemical Phenomena; D001671:Biochemistry; D002384:Catalysis; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008969:Molecular Sequence Data; D011118:Polynucleotide Ligases / Q000737:chemistry* / Q000378:metabolism*; D011130:RNA Ligase (ATP) / Q000737:chemistry* / Q000378:metabolism*; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors; D014158:Transcription, Genetic
D016337:RNA, Catalytic; D011118:Polynucleotide Ligases; C467725:R3C ligase; D011130:RNA Ligase (ATP)