RRC ID 6674
Author Inagaki Y, Doolittle WF.
Title Class I release factors in ciliates with variant genetic codes.
Journal Nucleic Acids Res.
Abstract In eukaryotes with the universal genetic code a single class I release factor (eRF1) most probably recognizes all stop codons (UAA, UAG and UGA) and is essential for termination of nascent peptide synthesis. It is well established that stop codons have been reassigned to amino acid codons at least three times among ciliates. The codon specificities of ciliate eRF1s must have been modified to accommodate the variant codes. In this study we have amplified, cloned and sequenced eRF1 genes of two hypotrichous ciliates, Oxytricha trifallax (UAA and UAG for Gln) and Euplotes aediculatus (UGA for Cys). We also sequenced/identified three protist and two archaeal class I RF genes to enlarge the database of eRF1/aRF1s with the universal code. Extensive comparisons between universal code eRF1s and those of Oxytricha, Euplotes, and Tetrahymena which represent three lineages that acquired variant codes independently, provide important clues to identify stop codon-binding regions in eRF1. Domain 1 in the five ciliate eRF1s, particularly the TASNIKS heptapeptide and its adjacent region, differs significantly from domain 1 in universal code eRF1s. This observation suggests that domain 1 contains the codon recognition site, but that the mechanism of eRF1 codon recognition may be more complex than proposed by Nakamura et al. or Knight and Landweber.
Volume 29(4)
Pages 921-7
Published 2001-2-15
PMID 11160924
PMC PMC29606
MeSH Amino Acid Sequence Amino Acid Substitution / genetics Animals Base Sequence Ciliophora / genetics* Cloning, Molecular Codon, Terminator / genetics Databases as Topic Dictyostelium / genetics Euplotes / genetics Genetic Code / genetics* Introns / genetics Kinetics Molecular Sequence Data Mutagenesis / genetics Oxytricha / genetics Peptide Termination Factors / chemistry* Peptide Termination Factors / classification Peptide Termination Factors / genetics Peptide Termination Factors / metabolism* Phylogeny Protein Structure, Tertiary Sequence Alignment Tetrahymena / genetics
IF 10.162
Times Cited 39
Cellular slime molds G01361