Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae
Thesis (MSc) -- University of Stellenbosch, 1998.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : Stellenbosch University
2012
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613969839030274 |
|---|---|
| access_status_str | Open Access |
| author | Gagiano, Marco |
| author2 | Pretorius, I. S. |
| author_browse | Gagiano, Marco Pretorius, I. S. |
| author_facet | Pretorius, I. S. Gagiano, Marco |
| author_sort | Gagiano, Marco |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc) -- University of Stellenbosch, 1998. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/55831 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:35.400Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/55831 Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae Gagiano, Marco Pretorius, I. S. Lambrechts, M. G. Stellenbosch University. Faculty of Science. Dept. of Microbiology. Saccharomyces cerevisiae -- Genetics Biological control systems Genetic transcription Repressors, Genetic Eukaryotic cells Chromatin Dissertations -- Microbiology Thesis (MSc) -- University of Stellenbosch, 1998. The STA1-3 genes of the budding yeast, Saccharomyces cerevisiae, encode extracellular glucoamylase isozymes. These enzymes enable the yeast cell to utilise starch as a carbon source by liberating glucose from the starch molecule’s non-reducing end, thereby making it accessible to the yeast cell. The MUC1 gene, however, encodes a cell-wall protein that structurally resembles mucins from higher organisms such as mammals, and plays an important role in the ability of the yeast cell to develop elongated chains of cells (pseudohyphae), to aggregate in a process called flocculation and to invade the growth substrate. The STA1-3 genes are subject to complex regulation. The transcription thereof is repressed on most carbon sources including galactose, sucrose and glucose, in most diploid strains of S. cerevisiae as well as in strains containing an undefined repressor, STA10. The repressive effect of chromatin on the transcription of STA1-3 is also implied in that Ssd1p, a chromatin-associated protein, was identified as a repressor of STA1-3 transcription. Several components of the SWI-SNF activation complex were also identified as positive regulators of STA1-3 transcription. This complex relieves the repressive effect of chromatin on the promoters of several genes. The MUC1 and STA1-3 genes are probably regulated in a largely similar manner, since the nucleotide sequences of the areas upstream of the open reading frames are almost identical. The identification of Msn1p as an activator of both STA2 and MUC1 transcription confirmed that these genes are probably co-regulated. A second transcriptional activator of STA2, Mss11p, has also been identified recently, but it has not yet been identified as a transcriptional activator of MUC1. Several areas upstream of the STA1-3 open reading frame were identified as elements involved in the transcriptional regulation of the genes. Two areas of specific interest, UAS1 and UAS2, were identified as areas through which activation of STA1-3 occurs as well as through which repression by means of STA10 is mediated. Although the promoters of STA1-3 and MUC1 are almost identical, the only dissimilarities occur as two inserts of 20 nucleotides and 64 nucleotides in the promoter of MUC1 but not in the STA1-3 promoter. The 20 nucleotide insert is located within the UAS1 area whereas the 64 nucleotide insert is situated downstream thereof. To elucidate the mechanism of transcriptional regulation of MUC1 and STA1-3, and to identify the functional relevance of the 20 nucleotide MUC1 insert in the UAS1 area, sequential deletions of the UAS1 region was made and inserted into a CYC1 promoter, fused to the lacZ reporter gene. The effect of these deletions on the expression of the lacZ gene was monitored in different genetic backgrounds and on different carbon sources. In this way several areas within the UAS1 region were identified as elements through which regulation occurs. An area resulting in increased expression of the reporter gene on media containing glucose was identified. This area does not contain any consensus binding sites for known repressor proteins involved in glucose repression. It is therefore possible that other, or even novel proteins, are involved in the transcription of STA1-3 and MUC1 on glucose media but that it functions through the identified element. An area subject to repression by the STA10 repressor was also identified. In addition, it was also shown that the repressive effect of STA10 is more pronounced on starch than on any of the other carbon sources. The area immediately downstream of the STA10 repressed area was also identified as necessary for starch-specific derepression. These facts suggest a nutritional signal, activated specifically in response to starch that results in elevated levels of transcription in sta10 backgrounds and severe repression in STA10 backgrounds. When present in multiple copies, the transcriptional activator of STA2, Mss11p, results in elevated expression levels of constructs containing the MUC1 UAS1 area. It is also shown that Mss11p does not act through the UAS1 promoter region to confer transcriptional activation of STA2 and MUC1. The 20 nucleotide insert of the MUC1 promoter seems to play a role in repression of MUC1 transcription on media containing glycerol and ethanol. Constructs containing the UAS1 area in which the 20 nucleotide insert is present, resulted in significantly lower levels of reporter gene expression compared to constructs that do not contain the insert on glycerol and ethanol media. It further seems that the activating effect of Mss11p is more pronounced in constructs containing this insert, implying that Mss11p acts in part through this element. This study answers several questions concerning the regulation of STA1-3 and MUC1 transcription at promoter level and serves as a foundation for further, more detailed studies to elucidate the mechanism of regulation. In conclusion, a model in which STA1-3 and MUC1 transcription is repressed mainly through the effect of chromatin and derepressed by specific activators, is proposed. Masters 2012-08-27T11:37:15Z 2012-08-27T11:37:15Z 1998 Thesis http://hdl.handle.net/10019.1/55831 en Stellenbosch University 121 pages : ill. Stellenbosch : Stellenbosch University |
| spellingShingle | Saccharomyces cerevisiae -- Genetics Biological control systems Genetic transcription Repressors, Genetic Eukaryotic cells Chromatin Dissertations -- Microbiology Gagiano, Marco Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title | Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title_full | Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title_fullStr | Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title_full_unstemmed | Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title_short | Cis-acting elements involved in the transcriptional control of the glucoamylase and mucin genes of Saccharomyces cerevisiae |
| title_sort | cis acting elements involved in the transcriptional control of the glucoamylase and mucin genes of saccharomyces cerevisiae |
| topic | Saccharomyces cerevisiae -- Genetics Biological control systems Genetic transcription Repressors, Genetic Eukaryotic cells Chromatin Dissertations -- Microbiology |
| url | http://hdl.handle.net/10019.1/55831 |
| work_keys_str_mv | AT gagianomarco cisactingelementsinvolvedinthetranscriptionalcontroloftheglucoamylaseandmucingenesofsaccharomycescerevisiae |