CO 2
CO 2
RuBisCO
phytochromobilin Pr Pfr
CO 2
1 CO2
a b
b CHO a a -
H+ H+ e - e - Mn Yz e - Q B P680 Q A Mn Yz P680 Q A Q B e ē - e - Mn Yz P680 Q A Q B Mn e - Yz P680 e - Q A Q B H 2 O Mn Yz e - P680 e - Q A Q B O 2 H + Mn Yz e - P680 e - Q A Q B PSI
Chl Chl Light-harvesting chlorophyll, LHC Chl Chl Chl Chl Chl Chl Chl NADPH Chl Chl Chl H + (CH 2 O) n CO 2 Chl Chl Chl Chl Chl a Chl H + b Chl Chl Chl ATP Chl Chl Chl H + γ β δ α β α c β ε α ADP + Pi ATP ATP
- 800 mv Q A /Q B PS II 600 + mvh 2 O ½O 2 Z Scheme Fe-S b6/f - 400 mv NADP NADP NADPH - 340 mv PS I
CO 2
CO 2 /O 2 RuBP GAP SBP F6P R5P R5P S7P Xu5P SBP Ru5P E4P FBP FBP GAP Xu5P DPGA Ru5P RuBP RuBisCO PGA TP DAHP TP CO 2 O 2 PGA glycolate GAP RuBP glyoxylate glycine P-glycolate PCO serine glycerate CO2O2 hydroxypyruvate O 2 ATP, NADPH
RuBisCO CO2 O2 CH2OPO3 - C=O HC-OH HC-OH CH2OPO3 - RuBP C-OH C-OH HC-OH * CH2OPO3 - CH2OPO3 - O 2 CO2 HO - HO - CH2OPO3 - CH2OPO3 - C-COO * - HO C-COO * - C=O - HO-C-OH HC-OH CH2OPO3 - CH2OPO3 - C-OO - C=O HC-OH CH2OPO3 - HC-OH CH2OPO3 - CH2OPO3 - HO C-OO - - HO-C-OH HC-OH CH2OPO3 - CH 2OPO3 - HC-OH * COO - + COO - HC-OH CH2OPO3 - PGA CH2OPO3 - COO - + COO - HC-OH CH2OPO3 - PGA
Ci Sr = Vcmax/Kcm)/(Vomax/Kom) CO 2 O 2 CO2 C C SS CO2 O2 Ci Ci Sr
-1,6- C6-6- C6 C3) C3) C12) C12) Cn
RuBisCO GAP R5P R5P S7P Xu5P SBP SBP Ru5P Xu5P Ru5P RuBP F6P E4P FBP FBP GAP CO 2 O 2 DPGA RuBP RuBisCO PGA TP DAHP TP PGA glycolate GAP glyoxylate glycine P-glycolate PCO serine glycerate O 2 hydroxypyruvate
CO2 photons
CO 2
2000 CO2
CO 2 /O 2 CO 2 SuperRuBisCO 100 200 300 400 500 600 CO 2 (ppm)
PNAS (1997) Science (2003) (rbcs) Cross-talk mrna (rbcl) RuBP mrna worse RuBisCO Form I of cyanobacteria, green algae and higher plants Form II k cat :3-8 s -1 site -1 S rel :10-90 BBRC (2003) JMB (2002) JBC (1997) PCR/PCO cycles CO2/O2 RuBP better RuBisCO Form I of Galdieria and some red algae S rel :240 Engineered Form I k cat :16 s -1 site -1 FEBS Lett. (2002) JB (2001) JBC (1999) BBRC (1997)
CO 2 O 2RuBisCO O2 T65 K177 E60 N123 R295 CO 2 RuBisCO RuBisCO CO 2 O 2 RuBisCO RuBisCO loop 6 CO 2 O 2 O 2
1 CO 2 500-1000 CO 2
CO 2 CO 2 CO 2
Late Embryogenesis Abundant (LEA)
P680 II ATP 2 H + NADPH NADP + + 2 H + CF1 α β LHC2 Phe QA QB P680 D2 D1 Mn 33kD 1/2 O2 27kD H2O + 17kD 2 H + PCR/PCO PQ LHC2 PQ PQ 2 H + Cyt.b6 Cyt.f RuBisCO Fd FNR A Fe-S CF0 P700 PC 3 H + 3 H + ADP + Pi P700 I
OH O 2 - SOD OH NADP GSH H 2 O 2 V.C GSSG NADPH GR GPX APXMDARDHAR GR NADPH GSSG H 2 O MDV.C GSH NADP V.C
A B 1 2 Nos-pro LB NPTII V S C M S Q GTC AGT TGC ATG TCG CAA transit peptide HindIII Nos-ter pro KatE tomato rbcs3c gene StuI/SstI Nos-ter RB 93kD Wild tobacco Transformants
µmol/mg protein/min µmol/mg chlorophyll/h nmol/mg protein/min 100 50 2.0 1.0 200 100 cyt chl wild transformant CO2 fix Ru5PK APX 0 hr 48 hr 0 hr 48 hr NADP + O2 e- Photosystems 1/2 O2 PCR/PCO Cycles GSH/ GSSG O2 - /H2O2 H2O DHAR? H2O Ascorbate APX Monodehydro -ascorbate Dehydroascorbate H2O Chloroplast
1 Craterostigma
H 2 N : NH 2 C=O NH CH 2 CH 2 CH 2 CH COOH #. #. #. 40 30 20 10 0 0.5% 0 3 8 Citrulline Arginine Glutamic acid Glutamine Alanine Serine Aspartic acid (M -1 s -1 ) (3.9 + 0.82) X 10 9 (2.1 + 0.58) X 10 9 (5.4 + 0.94) X 10 8 (8.2 + 0.31) X 10 7 Kawasaki et. al., (2000) Plant Cell Physiol., 41, 864-873 Akashi, et al., (2001) FEBS Lett. 508, 438-442
b 561 ε-
CO 2
rbcl mrna RNA/ 3500 DNA DNA Gppp AAAAA DNA10,000 copies/cell Gene Dosage
mrna CO2
2004829 93
CO 2
CO 2 O 2 R5P R5P S7P Xu5P SBP SBP Ru5P Xu5P Ru5P RuBP glyoxylate GAP E4P F6P FBP FBP DPGA CO 2 O 2 RuBP RuBisCO PGA PGA GAP GAP glycolate glycine P-glycolate PCO serine glycerate hydroxypyruvate TP DAHP TP
UP RuBisCO CO2 UP
RuBisCO