Abstract
The carbonic anhydrase (PtCA1) in the marine diatom Phaeodactylum tricornutum is regulated in response to changes in the ambient [CO2]. Our previous studies have shown that critical CO2-response region of the (Pptca1) promoter, comprises a cAMP-response element (CRE1) and a p300-binding site (p300bs) within -70 to -10bp relative to the transcription start site. In the present study, we attempted to model a fundamental structure of promoter in response to CO2. CRE1 or p300bs was fused directly to minimal promoter of Pptca1 (mPptca1), and its transcriptional activities were evaluated. As results, CRE1 could confer mPptca1 with clear CO2 response whereas p300bs could not, indicating that CRE1 is one of critical elements for CO2 response. Meanwhile, three anti parallel repeat sequences located overlapping to CRE1 and p300bs and upstream region of CRE1 were recently found to be related in response to CO2. Topological relations of these putative cis-elements will be discussed.
