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Evolution of the Genetic Code in the Ascoideales (CUG-Ser2) Yeast Clade: The Ancestral tRNA-Leu(CAG) Gene Is Retained in Most Saccharomycopsis Species but Is Nonessential and Not Used for Translation.
Ó Cinnéide, Eoin; Scaife, Caitriona; Dillon, Eugène T; Wolfe, Kenneth H.
Afiliación
  • Ó Cinnéide E; UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland.
  • Scaife C; Mass Spectrometry Core Facility, UCD Conway Institute, University College Dublin, Dublin, Ireland.
  • Dillon ET; Mass Spectrometry Core Facility, UCD Conway Institute, University College Dublin, Dublin, Ireland.
  • Wolfe KH; UCD Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland.
Genome Biol Evol ; 16(8)2024 Aug 05.
Article en En | MEDLINE | ID: mdl-39081261
ABSTRACT
In the yeast genera Saccharomycopsis and Ascoidea, which comprise the taxonomic order Ascoideales, nuclear genes use a nonstandard genetic code in which CUG codons are translated as serine instead of leucine, due to a tRNA-Ser with the unusual anticodon CAG. However, some species in this clade also retain an ancestral tRNA-Leu gene with the same anticodon. One of these species, Ascoidea asiatica, has been shown to have a stochastic proteome in which proteins contain ∼50% Ser and 50% Leu at CUG codon sites, whereas previously examined Saccharomycopsis species translate CUG only as Ser. Here, we investigated the presence, conservation, and possible functionality of the tRNA-Leu(CAG) gene in the genus Saccharomycopsis. We sequenced the genomes of 23 strains that, together with previously available data, include almost every known species of this genus. We found that most Saccharomycopsis species have genes for both tRNA-Leu(CAG) and tRNA-Ser(CAG). However, tRNA-Leu(CAG) has been lost in Saccharomycopsis synnaedendra and Saccharomycopsis microspora, and its predicted cloverleaf structure is aberrant in all the other Saccharomycopsis species. We deleted the tRNA-Leu(CAG) gene of Saccharomycopsis capsularis and found that it is not essential. Proteomic analyses in vegetative and sporulating cultures of S. capsularis and Saccharomycopsis fermentans showed only translation of CUG as Ser. Despite its unusual structure, the tRNA-Leu(CAG) gene shows evidence of sequence conservation among Saccharomycopsis species, particularly in its acceptor stem and leucine identity elements, which suggests that it may have been retained in order to carry out an unknown nontranslational function.
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Texto completo: 1 Banco de datos: MEDLINE Asunto principal: Evolución Molecular Idioma: En Revista: Genome Biol Evol Asunto de la revista: BIOLOGIA / BIOLOGIA MOLECULAR Año: 2024 Tipo del documento: Article País de afiliación: Irlanda

Texto completo: 1 Banco de datos: MEDLINE Asunto principal: Evolución Molecular Idioma: En Revista: Genome Biol Evol Asunto de la revista: BIOLOGIA / BIOLOGIA MOLECULAR Año: 2024 Tipo del documento: Article País de afiliación: Irlanda