The KlCYC1 gene, a downstream region for two differentially regulated transcripts

Abstract

KlCYC1 encodes for cytochrome c in the yeast Kluyveromyces lactis and is transcribed in two mRNAs with different 3'-processing points. This is an uncommon transcription mechanism in yeast mRNAs. The 3' sequence encompassing the whole region that is needed to produce both mRNAs is analysed. We have determined identical processing points in K.lactis and in Saccharomyces cerevisiae cells transformed with KlCYC1; positions 698 and 1092 (with respect to the TAA) are the major polyadenylation points. This shows that the cis-elements present in the KlCYC1 3'-untranslated region (3'-UTR) direct a processing mechanism that has been conserved in yeast. In K. lactis there is a high predominance of the shorter transcript (1.14 kb) only at the initial logarithmic growth phase. Interestingly, this growth phase-dependent regulation of 3'-UTR processing is lost when the gene is expressed in S. cerevisiae.

The Expanding Landscape of Moonlighting Proteins in Yeasts

“…The term gene sharing, first proposed for these proteins (3), may present some ambiguities, as there are cases in which a gene may encode different protein forms. In yeasts, this can be due to different sites for initiation of translation (6,7), termination (8), or splicing (9). In these cases, the corresponding protein forms also share a gene but this gene sharing is not the same as that of a single protein playing two different roles.…”

Alternative Polyadenylation in Yeast: 3 ́-UTR Elements and Processing Factors Acting at a Distance

“…The previous analyses showed that the KlCYC1 3´-UTR contains multiple putative processing elements but most of them do not match canonical consensus (Freire-Picos et al, 2001). In Figure 2A the RNA processing prediction output for KlCYC1 3´-UTR (S. cerevisiae mRNA 3'-processing site predictor) is shown.…”

“…Regarding the UTR length and the possibility of APA regulation, there are genes processed with regulatory alternatives. In these the alternative processing positions allow to differentiate transcripts (ie, HIS3 with 13 sites (Mahandevan et al, 1997), SUA7 with two transcripts (1.2 and 1.4) (Hoopes et al, 2000) or the two KlCYC1 (1.14 kb and 1.5 kb) (Freire-Picos et al, 2001). The genes with apparently non-regulatory alternatives are where the alternative sites are separated by as few as 10-11 nucleotides in the ACT1 transcripts (Gallwith et al, 1981) or the seven variants of YPT1 3´-end transcripts (Heidmann et al, 1992).…”

“…The two KlCYC1 transcripts change their predominance along the growth phase, but not with the carbon source (Freire-Picos et al, 2001). We have shown that when the UTR is split after the first processing point, thereby separating the proximal or distal sequences, they may act as independent processing elements in both S. cerevisiae and K. lactis yeast species (Seoane et al, 2005).…”

“…ossMUT1C-2: 5´-GTTGATAATAGAAGTAGTAGAGTTGTTAAAAAAGAAAGAAATAA TCATAAAATTTGGTATTCTTGGAATAGTAGTACATAG-3´. Plasmid pCT2 (Freire-Picos et al, 2001) was used as KlCYC1 template for the site-directed mutagenesis experiments, and as a source of wild type 3´-UTR in expression experiments.…”