期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 117, 期 6, 页码 2906-2913出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1914282117
关键词
directed evolution; RNA enzyme; RNA replication
资金
- National Aeronautics and Space Administration [NSSC19K0481]
- Simons Foundation [287624]
- Natural Sciences and Engineering Research Council of Canada
- NIH [CCSG:P30 014195, GM102491, AG064049]
- Helmsley Trust
The RNA-based organisms from which modern life is thought to have descended would have depended on an RNA polymerase ribozyme to copy functional RNA molecules, including copying the polymerase itself. Such a polymerase must have been capable of copying structured RNAs with high efficiency and high fidelity to maintain genetic information across successive generations. Here the class I RNA polymerase ribozyme was evolved in vitro for the ability to synthesize functional ribozymes, resulting in the markedly improved ability to synthesize complex RNAs using nucleoside 5'-triphosphate (NTP) substrates. The polymerase is descended from the class I ligase, which contains the same catalytic core as the polymerase. The class I ligase can be synthesized by the improved polymerase as three separate RNA strands that assemble to form a functional ligase. The polymerase also can synthesize the complement of each of these three strands. Despite this remarkable level of activity, only a very small fraction of the assembled ligases retain catalytic activity due to the presence of disabling mutations. Thus, the fidelity of RNA polymerization should be considered a major impediment to the construction of a self-sustained, RNA-based evolving system. The propagation of heritable information requires both efficient and accurate synthesis of genetic molecules, a requirement relevant to both laboratory systems and the early history of life on Earth.
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