Journal
PLANT AND CELL PHYSIOLOGY
Volume 49, Issue 2, Pages 273-283Publisher
OXFORD UNIV PRESS
DOI: 10.1093/pcp/pcn003
Keywords
carbonic anhydrase; carbon-concentrating mechanism; carbon dioxide; photosynthesis; signal transduction; zinc
Categories
Ask authors/readers for more resources
In conditions with the poor availability of inorganic carbon (CO2 and HCO3-: Ci) for photosynthesis, aquatic photosynthetic organisms induce active Ci uptake systems that allow accumulation of Ci within the cell, the so-called carbon-concentrating mechanism (CCM). In a unicellular green alga, Chlamydomonas reinhardtii, a regulatory factor CCM1 is indispensable for the regulation of the CCM by sensing CO2 availability. CCM1 has two putative zinc-binding domains with several conserved cysteine and histidine residues in its N-terminal region. To determine whether the domains actually bind zinc atoms, the N-terminal parts of CCM1 were expressed as glutathione S-transferase fusion proteins and subjected to atomic absorption spectrometry. It was found that 1 mol of zinc is bound to 1 mol of amino acid regions 171 and 72101 of CCM1, respectively. In the case of the site-directed mutant proteins, H54Y, C77V and C80V, the zinc-binding ability was lost. Physiological analyses of the transgenic Chlamydomonas cells harboring a mutated Ccm1 gene revealed that amino acid residues such as C36, C41, H54, C77, C80, H90 and C93 were indispensable for induction of the CCM in response to Ci-limiting stress conditions. Size exclusion chromatography followed by immunoblot analyses indicated that CCM1 is present as a protein complex of approximately 290580 kDa independent of Ci availability.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available