Specific binding of a protein to a novel DNA element in the cyanobacterial small heat-shock protein gene.
Previously, it was shown that transcription of the small heat-shock protein gene, hspA, from the thermophilic cyanobacterium Synechococcus vulcanus is transiently heat-inducible at a vegetative promoter that lacks any known regulatory DNA elements. A novel regulatory mechanism that suppresses the expression of hspA under non-heat-shock condition has been postulated. In this study, it is demonstrated that a protein(s) in the extract of unstressed cells of the thermophilic cyanobacterium Thermosynechococcus elongatus, a cyanobacterium closely related to S. vulcanus, specifically binds to a 5'-untranslated region of the hspA gene. An AT-rich imperfect inverted-repeat sequence (ACAAgcAAA-TTTagTTGT) as a target for a putative DNA-binding protein has been identified. The DNA-binding activity in the cell as well as in the cell extract was lost much more quickly at a heat-shock temperature than a normal growth temperature. In a cell, the activity was restored within 45 min after a heat-shock by the heat-induced synthesis and stabilization of a DNA-binding protein. It is proposed that the inverted repeat is a specific target for a DNA-binding protein and that it plays a role in the regulation of the cyanobacterial hspA gene expression.
Kojima
Kouji
K
Department of Biochemistry and Molecular Biology, Saitama University, Saitama 338-8570, Japan.
Nakamoto
Hitoshi
H
D020121:5' Untranslated Regions / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid
D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; C113725:HspA protein, bacteria