Heat shock inducibility of an archaeal TATA‐like promoter is controlled by adjacent sequence elements

Open Access
Publisher Website
Google Scholar
Abstract
The expression of a heat‐inducible cct1 (chaperonin‐containing Tcp‐1) family member gene is regulated at the transcription level in the archaeon Haloferax volcanii. Transcriptional fusions of the cct1 promoter region with a yeast proline tRNA reporter gene were constructed to analyse the functional domains of this archaeal heat shock promoter. Both basal and heat‐induced transcription of the reporter gene was directed by an archaeal consensus TATA element (5′‐TTTATA‐3′) centred 25 bp upstream of the transcription start site. Deletion mutagenesis indicated that the 5′ boundary of the cct1 regulatory region mapped to position − 37. Nucleotide alignment with the 5′ flanking regions of two additional cct‐related genes identified in H. volcanii showed a high degree of sequence conservation between positions +1 and − 37, especially in and immediately surrounding the TATA element of the putative core promoter. Mutational analysis of conserved sequences demonstrated that basal and heat‐induced transcription required sequence elements located upstream and downstream of the TATA‐box. These findings indicate that the regulatory sequences involved in heat‐induced transcription lie within the core promoter region and suggest that the mechanism controlling heat shock gene expression in H. volcanii differs from the bacterial and eukaryal strategies.