TY - JOUR
T1 - A Gal4-σ54 Hybrid Protein that Functions as a Potent Activator of RNA Polymerase II Transcription in Yeast
AU - Chen, Bo Shiun
AU - Sun, Zu Wen
AU - Hampsey, Michael
PY - 2001/6/29
Y1 - 2001/6/29
N2 - The bacterial σ54 protein associates with core RNA polymerase to form a holoenzyme complex that renders cognate promoters enhancer-dependent. Although unusual in bacteria, enhancer-dependent transcription is the paradigm in eukaryotes. Here we report that a fragment of Escherichia coli σ54 encompassing amino acid residues 29-177 functions as a potent transcriptional activator in yeast when fused to a Gal4 DNA binding domain. Activation by Gal4-σ54 is TATA-dependent and requires the SAGA coactivator complex, suggesting that Gal4-σ 54 functions by a normal mechanism of transcriptional activation. Surprisingly, deletion of the AHC1 gene, which encodes a polypeptide unique to the ADA coactivator complex, stimulates Gal4-σ54 -mediated activation and enhances the toxicity of Gal4-σ54. Accordingly, the SAGA and ADA complexes, both of which include Gcn5 as their histone acetyltransferase subunit, exert opposite effects on transcriptional activation by Gal4-α54. Gal4-σ54 activation and toxicity are also dependent upon specific σ54 residues that are required for activator-responsive promoter melting by σ54 in bacteria, implying that activation is a consequence of σ 54-specific features rather than a structurally fortuitous polypeptide fragment. As such, Gal4-σ54 represents a novel tool with the potential to provide insight into the mechanism by which natural activators function in eukaryotic cells.
AB - The bacterial σ54 protein associates with core RNA polymerase to form a holoenzyme complex that renders cognate promoters enhancer-dependent. Although unusual in bacteria, enhancer-dependent transcription is the paradigm in eukaryotes. Here we report that a fragment of Escherichia coli σ54 encompassing amino acid residues 29-177 functions as a potent transcriptional activator in yeast when fused to a Gal4 DNA binding domain. Activation by Gal4-σ54 is TATA-dependent and requires the SAGA coactivator complex, suggesting that Gal4-σ 54 functions by a normal mechanism of transcriptional activation. Surprisingly, deletion of the AHC1 gene, which encodes a polypeptide unique to the ADA coactivator complex, stimulates Gal4-σ54 -mediated activation and enhances the toxicity of Gal4-σ54. Accordingly, the SAGA and ADA complexes, both of which include Gcn5 as their histone acetyltransferase subunit, exert opposite effects on transcriptional activation by Gal4-α54. Gal4-σ54 activation and toxicity are also dependent upon specific σ54 residues that are required for activator-responsive promoter melting by σ54 in bacteria, implying that activation is a consequence of σ 54-specific features rather than a structurally fortuitous polypeptide fragment. As such, Gal4-σ54 represents a novel tool with the potential to provide insight into the mechanism by which natural activators function in eukaryotic cells.
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U2 - 10.1074/jbc.M102893200
DO - 10.1074/jbc.M102893200
M3 - Article
C2 - 11313364
AN - SCOPUS:0035968254
SN - 0021-9258
VL - 276
SP - 23881
EP - 23887
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 26
ER -