Screening of transcription factors that are related to CO₂ and light response in a marine diatom

Abstract

Carbonic anhydrase of Phaeodactylum tricornutum (PtCA1) is encoded by the nuclear genome and its expression is regulated at the transcriptional level by changes in the ambient [CO₂] and light. Critical region required for [CO₂] and light-responsive transcription of ptca1 were located between -70 and -30 bp relative to the transcription start site. This critical region contains four cis-elements, that is, two cAMP response elements (CRE1:Pptca1-70/-63,CRE2:Pptca1-21/-14), a p300-binding site (Pptca1-52/-46) and a Skn-1 binding site (Pptca1-35/-28). It is suggested that the Skn-1 binding site is involved in stimulation of PtCA1 expression in response to [low CO₂] and light. In this study, Yeast one-hybrid assay was done to identify transcription factors, which bind to Skn-1 binding site. As a result, 155 positive clones were obtained. Inserted sequences in these positive clones were determined.