Biochemistry, Biophysics, and Structural Biology Commons^™

Reduced Co2/O2 Specificity Of Ribulose-Bisphosphate Carboxylase/Oxygenase In A Temperature-Sensitive Chloroplast Mutant Of Chlamydomonas, Zhixiang Chen, Chris J. Chastain, Souhail R. Al-Abed, Raymond Chollet, Robert J. Spreitzer

Department of Biochemistry: Faculty Publications

The Chlamydomonas reinhardtii chloroplast mutant 68-4PP is phenotypically indistinguishable from wild type at 25°C but fails to grow photosynthetically at 35°C. It had about 30% of the wild-type level of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) holoenzyme and carboxylase activity when grown at 25°C, but less than 15% when grown at 35°C. Pulse-labeling with ³⁵S showed that the decrease in enzyme level at the restrictive temperature was not a result of reduced synthesis of enzyme subunits. The CO₂/O₂ specificity factor (V_cK_o/V_oK_c, where V_c and V_o are V_{max …}