Abstract
Aquatic photosynthetic-microorganisms including diatoms possess inorganic CO2-concentrating mechanism (CCM), when grown in air levels CO2. Carbonic anhydrase (CA) is known to be a key component in CCM. We have previously demonstrated that β-type CA (PtCA) is induced upon CO2 limitation and that light stimulates PtCA induction in the marine diatom Phaeodactylum tricornutum.
In order to elucidate the molecular mechanisms of light stimulation in PtCA expression, the function of PtCA promoter region was analyzed in relation to light conditions. Several length of upstream region of PtCA gene were isolated and were fused to GUS gene. The pattern of GUS expression sharply agreed with that observed in PtCA expression and responsibility for CO2 was well conserved with -1292/-70 regions. Responsibility of these truncated promoter regions for light stimulation effect on PtCA expression is reported.
