Eriksson P, Alipour H, Adler L, Blomberg A. Rap1p-binding sites in the saccharomyces cerevisiae GPD1 promoter are involved in its response to NaCl.
J Biol Chem 2000;
275:29368-76. [PMID:
10842169 DOI:
10.1074/jbc.m001663200]
[Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanisms involved in transcriptional regulation of the osmotically controlled GPD1 gene in Saccharomyces cerevisiae were investigated by promoter analysis. The GPD1 gene encodes NAD(+)-dependent glycerol-3-phosphate dehydrogenase, a key enzyme in the production of the compatible solute glycerol. By analysis of promoter deletions, we identified a region at nucleotides -478 to -324, in relation to start of translation, to be of great importance for both basal activity and osmotic induction of GPD1. Electrophoretic mobility shift and DNase I footprint analyses demonstrated protein binding to parts of this region that contain three consensus sequences for Rap1p (repressor activator protein 1)-binding sites. Actual binding of Rap1p to this region was confirmed by demonstrating enhanced electrophoretic mobility of the protein-DNA complex with extracts containing an N-terminally truncated version of Rap1p. The detected Rap1p-DNA interactions were not affected by changes in the osmolarity of the growth medium. Specific inactivation of the Rap1p-binding sites by a C-to-A point mutation in the core of the consensus showed that this factor is a major determinant of GPD1 expression since mutations in all three putative binding sites for Rap1p strongly hampered osmotic induction and drastically lowered basal activity. We also show that the Rap1p-binding sites appear functionally distinct; the most distal site (core of the consensus at position -386) exhibited the highest affinity for Rap1p and was strictly required for low salt induction (< or =0.6 m NaCl), but not for the response at higher salinities (> or =0.8 m NaCl). This indicates tha different molecular mechanisms might be operational for low and high salt responses of the GPD1 promoter.
Collapse