Combination of two regulatory elements in the Tetrahymena thermophila HSP70-1 gene controls heat shock activation.
The induction of heat shock genes (HSPs) is thought to be primarily regulated by heat shock transcription factors (HSFs), which bind target sequences on HSP promoters, called heat shock elements (HSEs). In this study, we investigated the 5' untranslated regions of the Tetrahymena thermophila HSP70-1 gene, and we found, in addition to the canonical and divergent HSEs, multiple sets of GATA elements that have not been reported previously in protozoa. By means of in vivo analysis of a green fluorescent protein reporter transgene driven by the HSP70-1 promoter, we demonstrate that HSEs do not represent the minimal regulatory elements for heat shock induction, since the HSP70-1 is tightly regulated by both HSE and GATA elements. Electrophoretic mobility shift assay also showed that HSFs are constitutively bound to the HSEs, whereas GATA elements are engaged only after heat shock. This is the first demonstration by in vivo analysis of functional HSE and GATA elements in protozoa. Furthermore, we provide evidence of a functional link between HSE and GATA elements in the activation of the heat shock response.
Department of Molecular, Cellular, and Animal Biology, University of Camerino, Via Gentile III da Varano, 62032 Camerino (MC), Italy. sabrina.barchetta@unicam.it
Sabrina
S
Barchetta
Antonietta
A
La Terza
Patrizia
P
Ballarini
Sandra
S
Pucciarelli
Cristina
C
Miceli
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006358:Hot Temperature; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D016808:Tetrahymena thermophila / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D018840:HSP70 Heat-Shock Proteins; C081884:heat-shock protein 70.1