Premium
Acclimation to low [CO 2 ] by an inorganic carbon‐concentrating mechanism in Cyanophora paradoxa
Author(s) -
BUREY S. C.,
POROYKO V.,
ERGEN Z. N.,
FATHINEJAD S.,
SCHÜLLER C.,
OHNISHI N.,
FUKUZAWA H.,
BOHNERT H. J.,
LÖFFELHARDT W.
Publication year - 2007
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2007.01715.x
Subject(s) - chlamydomonas reinhardtii , rubisco , carbonic anhydrase , ribulose , complementary dna , biology , biochemistry , gene , botany , chemistry , enzyme , mutant
The glaucocystophyte Cyanophora paradoxa contains cyanelles, plastids with prokaroytic features such as a peptidoglycan wall and a central proteinaceous inclusion body. While this central body includes the majority of the enzyme ribulose 1,5‐bisphosphate carboxylase/oxgenase Rubisco), the presence of a carbon‐concentrating mechanism (CCM) in C. paradoxa has only been hypothesized. Here, we present physiological data in support of a CCM: CO 2 exchange activity as well as apparent affinity against inorganic carbon were found to increase under CO 2 ‐limiting stress. Further, expressed sequence tags (ESTs) of C. paradoxa were obtained from two cDNA libraries, one from cells grown in high [CO 2 ] conditions and one from cells grown under low [CO 2 ] conditions. A cDNA microarray platform assembled from 2378 cDNA sequences revealed that 142 genes significantly responded to a shift from high to low [CO 2 ]. Trends in gene expression were comparable to those reported for Chlamydomonas reinhardtii and the cyanobacterium Synechocystis 6803, both possessing a CCM. Among genes regulated by [CO 2 ], transcripts were identified encoding carbonic anhydrases (CAs), Rubisco activase and a putative bicarbonate transporter in C. paradoxa, likely functionally involved in the CCM. These results and the polyhedric appearance of the central body further support the hypothesis of a unique ‘eukaryotic carboxysome’ in Cyanophora .