title: Sensing of Elevating CO(2) in a Marine Diatom: Molecular Mechanisms and Implications.
abstract: One of the critical parts of the CO(2) perception mechanisms in algae has now been identified in a marine diatom, an important finding since diatoms are the major primary producer in the ocean. Increasing CO(2) might probably be sensed directly by the cAMP forming enzyme, adenylyl cyclase, and cytosolic cAMP represses expression of CCM components in marine diatoms. Upstream sequences of CO(2)-responsive genes, ptca1 and 2, for carbonic anhydrases (CA) in the marine diatom Phaeodactylum tricornutum, were recently isolated and characterized. Promoters for both ptca1 and 2 possess at least 5 CREs respectively at -10 to -330 and at -330 to -630 relative to each transcription-start site. Our recent experiments clearly showed that one of CREs, located at -70 to -63 of the ptca1 promoter, exhibited a primary role in repressing the ptca1 promoter under high CO(2) or in the dark. Truncations of CREs in the ptca2 promoter also resulted in derepressions of the ptca2 gene in high CO(2). This addendum will discuss the implication of acquiring repression systems for the CCM and the possible impact of the repression of the CCM following a direct perception of elevated [CO(2)] in the marine environment.
authors.affiliation: Department of Bioscience; Kwansei-Gakuin University; Hyogo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Hisashi
authors.initials: H
authors.lastname: Harada
authors.forename: Kensuke
authors.initials: K
authors.lastname: Nakajima
authors.forename: Brian
authors.initials: B
authors.lastname: Colman
references.citation: Plant Physiol. 2006 Nov;142(3):1318-28
references.pmid: 17012409
references.citation: Biochem J. 2006 Jun 1;396(2):e5-7
references.pmid: 16703664
references.citation: Plant Physiol. 1997 May;114(1):237-44
references.pmid: 9159949
references.citation: Plant Physiol. 2005 May;138(1):207-17
references.pmid: 15849303
references.citation: Plant Physiol. 1996 Apr;110(4):1283-1291
references.pmid: 12226260
references.citation: Plant Physiol. 2001 Aug;126(4):1459-70
references.pmid: 11500545
references.citation: Plant Physiol. 2005 Oct;139(2):1041-50
references.pmid: 16169965
references.citation: Science. 2000 Jul 28;289(5479):625-8
references.pmid: 10915626
references.citation: Mol Microbiol. 2005 Apr;56(2):549-58
references.pmid: 15813743