Dramatic difference in the responses of phosphoenolpyruvate carboxylase to temperature in leaves of C3 and C4 plants.

نویسندگان

  • Bhaskarrao Chinthapalli
  • Jhadeswar Murmu
  • Agepati S Raghavendra
چکیده

Temperature caused phenomenal modulation of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaf discs of Amaranthus hypochondriacus (NAD-ME type C(4) species), compared to the pattern in Pisum sativum (a C(3) plant). The optimal incubation temperature for PEPC in A. hypochondriacus (C(4)) was 45 degrees C compared to 30 degrees C in P. sativum (C(3)). A. hypochondriacus (C(4)) lost nearly 70% of PEPC activity on exposure to a low temperature of 15 degrees C, compared to only about a 35% loss in the case of P. sativum (C(3)). Thus, the C(4) enzyme was less sensitive to supra-optimal temperature and more sensitive to sub-optimal temperature than that of the C(3) species. As the temperature was raised from 15 degrees C to 50 degrees C, there was a sharp decrease in malate sensitivity of PEPC. The extent of such a decrease in C(4) plants (45%) was more than that in C(3) species (30%). The maintenance of high enzyme activity at warm temperatures, together with a sharp decrease in the malate sensitivity of PEPC was also noticed in other C(4) plants. The temperature-induced changes in PEPC of both A. hypochondriacus (C(4)) and P. sativum (C(3)) were reversible to a large extent. There was no difference in the extent of phosphorylation of PEPC in leaves of A. hypochondriacus on exposure to varying temperatures, unlike the marked increase in the phosphorylation of enzyme on illumination of the leaves. These results demonstrate that (i) there are marked differences in the temperature sensitivity of PEPC in C(3) and C(4) plants, (ii) the temperature induced changes are reversible, and (iii) these changes are not related to the phosphorylation state of the enzyme. The inclusion of PEG-6000, during the assay, dampened the modulation by temperature of malate sensitivity of PEPC in A. hypochondriacus. It is suggested that the variation in temperature may cause significant conformational changes in C(4)-PEPC.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Photosynthetic Characteristics and Antioxidative Responses in Three Species of Crassulaceae Following Drought Stress

Photosynthetic characteristics and induction of crassulacean acid metabolism (CAM) by drought stress were investigated in Sedum album, Sedum stoloniferum and Rosularia elymaitica from Crassulaceae. Titratable acidity, malate content, phosphoenolpyruvate carboxylase (PEPC) activity and gas exchange parameters were determined in plants at the end and beginning of the photoperiod. Results showed t...

متن کامل

Kranz and single-cell forms of C4 plants in the subfamily Suaedoideae show kinetic C4 convergence for PEPC and Rubisco with divergent amino acid substitutions

The two carboxylation reactions performed by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are vital in the fixation of inorganic carbon for C4 plants. The abundance of PEPC is substantially elevated in C4 leaves, while the location of Rubisco is restricted to one of two chloroplast types. These differences compared with C3 leaves have been...

متن کامل

Temperature modulation of the activity and malate inhibition of the phosphoenolpyruvate carboxylase from leaves of Alternanthera pungens, compared to that of Lycopersicom esculentum

Temperature caused marked modulation of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaf discs of Alternanthera pungens (C4 plant) as well as Lycopersicon esculentum (C3 species). The optimal incubation temperature for PEPC activity in A. pungens was 45 °C compared to 30 °C in L. esculentum. A. pungens lost nearly 61% of PEPC activity on exposure to a low temperature of 15 °C, compar...

متن کامل

Temperature Responses of C4 Photosynthesis: Biochemical Analysis of Rubisco, Phosphoenolpyruvate Carboxylase, and Carbonic Anhydrase in Setaria viridis.

The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are cur...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Journal of experimental botany

دوره 54 383  شماره 

صفحات  -

تاریخ انتشار 2003