Peer-Reviewed Journal Details
Mandatory Fields
Heaphy, SM;Mariotti, M;Gladyshev, VN;Atkins, JF;Baranov, PV
2016
November
Molecular biology and evolution
Novel Ciliate Genetic Code Variants Including the Reassignment of All Three Stop Codons to Sense Codons in Condylostoma magnum
Validated
WOS: 58 ()
Optional Fields
TRANSLATIONAL TERMINATION EUPLOTES-OCTOCARINATUS EFFICIENCY DATABASE GENOME
33
2885
2889
mRNA translation in many ciliates utilizes variant genetic codes where stop codons are reassigned to specify amino acids. To characterize the repertoire of ciliate genetic codes, we analyzed ciliate transcriptomes from marine environments. Using codon substitution frequencies in ciliate protein-coding genes and their orthologs, we inferred the genetic codes of 24 ciliate species. Nine did not match genetic code tables currently assigned by NCBI. Surprisingly, we identified a novel genetic code where all three standard stop codons (TAA, TAG, and TGA) specify amino acids in Condylostoma magnum. We provide evidence suggesting that the functions of these codons in C. magnum depend on their location within mRNA. They are decoded as amino acids at internal positions, but specify translation termination when in close proximity to an mRNA 30 end. The frequency of stop codons in protein coding sequences of closely related Climacostomum virens suggests that it may represent a transitory state.
OXFORD
0737-4038
10.1093/molbev/msw166
Grant Details