The non-standard genetic code of Candida spp.: an evolving genetic code or a novel mechanism for adaptation?
- PMID: 9402014
- DOI: 10.1046/j.1365-2958.1997.5891961.x
The non-standard genetic code of Candida spp.: an evolving genetic code or a novel mechanism for adaptation?
Abstract
A number of yeasts of the genus Candida translate the standard leucine-CUG codon as serine. This unique genetic code change is the only known alteration to the universal genetic code in cytoplasmic mRNAs, of either eukaryotes or prokaryotes, which involves reassignment of a sense codon. Translation of CUG as serine in these species is mediated by a novel serine-tRNA (ser-tRNACAG), which uniquely has a guanosine at position 33, 5' to the anticodon, a position that is almost invariably occupied by a pyrimidine (uridine in general) in all other tRNAs. We propose that G-33 has two important functions: lowering the decoding efficiency of the ser-tRNACAG and preventing binding of the leucyl-tRNA synthetase. This implicates this nucleotide as a key player in the evolutionary reassignment of the CUG codon. In addition, the novel ser-tRNACAG has 1-methylguanosine (m1G-37) at position 37, 3' to the anticodon, which is characteristic of leucine, but not serine tRNAs. Remarkably, m1G-37 causes leucylation of the ser-tRNACAG both in vitro and in vivo, making the CUG codon an ambiguous codon: the polysemous codon. This indicates that some Candida species tolerate ambiguous decoding and suggests either that (i) the genetic code change has not yet been fully established and is evolving at different rates in different Candida species; or (ii) CUG ambiguity is advantageous and represents the final stage of the reassignment. We propose that such dual specificity indicates that reassignment of the CUG codon evolved through a mechanism that required codon ambiguity and that ambiguous decoding evolved to generate genetic diversity and allow for rapid adaptation to environmental challenges.
Similar articles
-
Transfer RNA structural change is a key element in the reassignment of the CUG codon in Candida albicans.EMBO J. 1996 Sep 16;15(18):5060-8. EMBO J. 1996. PMID: 8890179 Free PMC article.
-
Molecular reconstruction of a fungal genetic code alteration.RNA Biol. 2013 Jun;10(6):969-80. doi: 10.4161/rna.24683. Epub 2013 Apr 17. RNA Biol. 2013. PMID: 23619021 Free PMC article.
-
Characterization of serine and leucine tRNAs in an asporogenic yeast Candida cylindracea and evolutionary implications of genes for tRNA(Ser)CAG responsible for translation of a non-universal genetic code.Nucleic Acids Res. 1994 Jan 25;22(2):115-23. doi: 10.1093/nar/22.2.115. Nucleic Acids Res. 1994. PMID: 8121794 Free PMC article.
-
[The molecular mechanism of evolution of changes in the genetic code].Mol Biol (Mosk). 2006 Jul-Aug;40(4):634-9. Mol Biol (Mosk). 2006. PMID: 16913222 Review. Russian.
-
Evolution of the genetic code in yeasts.Yeast. 2006 Feb;23(3):203-13. doi: 10.1002/yea.1350. Yeast. 2006. PMID: 16498697 Review.
Cited by
-
Evolution of phage with chemically ambiguous proteomes.BMC Evol Biol. 2003 Dec 10;3:24. doi: 10.1186/1471-2148-3-24. BMC Evol Biol. 2003. PMID: 14667253 Free PMC article.
-
Evolution of microbial pathogens.Philos Trans R Soc Lond B Biol Sci. 2000 May 29;355(1397):695-704. doi: 10.1098/rstb.2000.0609. Philos Trans R Soc Lond B Biol Sci. 2000. PMID: 10874741 Free PMC article. Review.
-
Genome analysis of the yeast Diutina catenulata, a member of the Debaryomycetaceae/Metschnikowiaceae (CTG-Ser) clade.PLoS One. 2018 Jun 26;13(6):e0198957. doi: 10.1371/journal.pone.0198957. eCollection 2018. PLoS One. 2018. PMID: 29944657 Free PMC article.
-
A genetic code alteration generates a proteome of high diversity in the human pathogen Candida albicans.Genome Biol. 2007;8(10):R206. doi: 10.1186/gb-2007-8-10-r206. Genome Biol. 2007. PMID: 17916231 Free PMC article.
-
tRNomics: analysis of tRNA genes from 50 genomes of Eukarya, Archaea, and Bacteria reveals anticodon-sparing strategies and domain-specific features.RNA. 2002 Oct;8(10):1189-232. doi: 10.1017/s1355838202022021. RNA. 2002. PMID: 12403461 Free PMC article.
Publication types
MeSH terms
Substances
Grants and funding
LinkOut - more resources
Full Text Sources
Miscellaneous