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The two divergent PEP‐carboxylase catalytic subunits in the green microalga Chlamydomonas reinhardtii respond reversibly to inorganic‐N supply and co‐exist in the high‐molecular‐mass, hetero‐oligomeric Class‐2 PEPC complex
Author(s) -
Moellering Eric R.,
Ouyang Yexin,
Mamedov Tarlan G.,
Chollet Raymond
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.09.015
Subject(s) - chlamydomonas reinhardtii , phosphoenolpyruvate carboxylase , homotetramer , biochemistry , pyruvate carboxylase , molecular mass , biology , gene , protein subunit , enzyme , rubisco , chlamydomonas , chemistry , mutant
Our recent molecular studies revealed two divergent PEP‐carboxylase (PEPC [Ppc]) encoding genes in the green microalga Chlamydomonas reinhardtii , CrPpc1 and CrPpc2 , which are coordinately responsive to changes in inorganic‐N and ‐C supply at the transcript level [Mamedov, T.G., Moellering, E.R. and Chollet, R. (2005) Identification and expression analysis of two inorganic C‐ and N‐responsive genes encoding novel and distinct molecular forms of eukaryotic phosphoenolpyruvate carboxylase in the green microalga C. reinhardtii , Plant J. 42, 832–843]. Here, we report the distribution of these two encoded catalytic subunits in the minor Class‐1 and predominant Class‐2 PEPC enzyme‐forms, the latter of which is a novel high‐molecular‐mass, hetero‐oligomeric complex containing both CrPpc1 (p109) and CrPpc2 (p131) polypeptides. The Class‐1 enzyme, however, is a typical PEPC homotetramer comprised solely of p109. We also document that the amount of both CrPpc1/2 catalytic subunits is up‐/down‐regulated by varying levels ofNH 4 +supplied to the culture medium.