Elsevier

Biochimie

Volume 76, Issue 12, 1994, Pages 1217-1222
Biochimie

Unique structure of new serine tRNAs responsible for decoding leucine codon CUG in various Candida species and their putative ancestral tRNA genes

https://doi.org/10.1016/0300-9084(94)90052-3Get rights and content

Abstract

In an asporogenic yeast, Candida cylindracea, codon CUG is not translated as leucine but as serine. On the basis of our recent work on the determination of the genetic code using in vitro translation systems coupled with isolation of the corresponding tRNA molecules, it appears that this non-universal genetic code is unitized not only in C cylindracea but also in various Hemiascomycetes. Here we show that in addition to the species already reported, three pathogenic yeast, C guilliermondii, C lusitaniae and C tropicalis, have tRNASerCAG, indicating that this non-universal genetic code (CUG=Ser) also exists in these species. Determination of their primary structures revealed that the uridine conserved at position 33 in usual tRNAs, is replaced by guanosine or cytidine. This suggests that the three-dimensional structures of the anticodon loop of these tRNAs differ from the conventional structure comprising the U turn in this position. Moreover, we succeeded in isolating putative ancestral serine tRNA genesw hose sequences are highly homologous to tRNASerCAG in each case. These tRNA genes all have the anticodon sequence CGA corresponding to the codon UCG, indicating that tRNASerCAG might have emerged from tRNASerCGA during evolutionary change of the assignment of codon CUG.

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Cited by (25)

  • Genomic Exploration of the hemiascomycetous yeasts: 3. Methods and strategies used for sequence analysis and annotation

    2000, FEBS Letters
    Citation Excerpt :

    With regard to yeasts, it was originally discovered using cell-free translation experiments, that the standard leucine codon CUG encodes a serine in Candida cylindracea [71]. The same was subsequently found to apply to a variety of other Candida species, including C. albicans and C. tropicalis [72], while a larger exploration of the Candida genus showed 66 species using the CUG codon for serine and 11 others for leucine [73]. This last study included Candida famata, the anamorph of D. hansenii used in our program.

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