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Genetic Codes with No Dedicated Stop Codon: Context-Dependent Translation Termination.

ABSTRACT: The prevailing view of the nuclear genetic code is that it is largely frozen and unambiguous. Flexibility in the nuclear genetic code has been demonstrated in ciliates that reassign standard stop codons to amino acids, resulting in seven variant genetic codes, including three previously undescribed ones reported here. Surprisingly, in two of these species, we find efficient translation of all 64 codons as standard amino acids and recognition of either one or all three stop codons. How, therefore, does the translation machinery interpret a "stop" codon? We provide evidence, based on ribosomal profiling and "stop" codon depletion shortly before coding sequence ends, that mRNA 3' ends may contribute to distinguishing stop from sense in a context-dependent manner. We further propose that such context-dependent termination/readthrough suppression near transcript ends enables genetic code evolution.

SUBMITTER: Swart EC

PROVIDER: S-EPMC4967479 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Genetic Codes with No Dedicated Stop Codon: Context-Dependent Translation Termination.

Swart Estienne Carl EC Serra Valentina V Petroni Giulio G Nowacki Mariusz M

Cell 20160714 3

The prevailing view of the nuclear genetic code is that it is largely frozen and unambiguous. Flexibility in the nuclear genetic code has been demonstrated in ciliates that reassign standard stop codons to amino acids, resulting in seven variant genetic codes, including three previously undescribed ones reported here. Surprisingly, in two of these species, we find efficient translation of all 64 codons as standard amino acids and recognition of either one or all three stop codons. How, therefore ...[more]

PMID: 27426948

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