Ubiquitin genes in Tetrahymena pyriformis and their expression during heat shock

Ana M. Neves, Isabel Barahona, Lisete Galego, Claudina Rodrigues-Pousada

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The genome of Tetrahymena pyriformis was shown to contain a ubiquitin multigene family consisting of at least four polyubiquitin genes. Three genomic clones with different ubiquitin-coding sequences, were isolated and partially characterized. The complete nucleotide sequence of one of these clones (pTU2) was determined and showed two open reading frames (ORFs) at opposite ends of the cloned DNA insert. A comparison of the predicted amino acid (aa) sequence of T. pyriformis ubiquitin-coding unit with those from other organisms indicated a high degree of homology. However, Tetrahymena ubiquitin contained two aa substitutions at positions 16 (Asp) and 19 (Ala). Interestingly, the first pTU2 ORF showed two extra triplets coding for Ser and Gin, upstream from TGA. This feature is different from all the polyubiquitin genes thus far sequenced. Regions flanking the 3' and 5' ubiquitin-coding sequences presented several conserved motifs. The 5' flanking sequence of the second ORF of pTU2 contained one heat-shock element. We therefore studied the expression of the ubiquitin genes under stress conditions. The results showed that they are heat-inducible and that a new specific 1.6-kb mRNA appeared. These results suggest that the regulation of ubiquitin genes is important in T. pyriformis under thermal stress conditions.

Original languageEnglish
Pages (from-to)87-96
Number of pages10
JournalGene
Volume73
Issue number1
DOIs
Publication statusPublished - 15 Dec 1988
Externally publishedYes

Keywords

  • Recombinant DNA
  • amino acid homology
  • gene cloning
  • heat shock element
  • heat-specific induction
  • polyubiquitin

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