DnaA is an ATP-binding protein.

The first stage in initiation is binding of the DnaA-ATP protein complex to the fully methylated oriC sequence.

This takes place in association with the inner membrane. DnaA is in the active form only when bound to ATP.

DnaA has intrinsic ATPase activity that hydrolyzes ATP to ADP and thus inactivates itself when the initiation stage ends.

TLS Online TPP Program

#Id: 7298

#Unit 6. System Physiology – Plant

PPDK-RP make PPDK active removing phosphates of catalytic his/threo residues using ADP as phosphoryl donor, rather than ATP, and the phosphorolytic dephosphorylation of the (PPDK)−Thr−O−P with formation of pyrophosphate, rather than the hydrolysis employed by most protein

phosphatases.

TLS Online TPP Program

#Id: 7299

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 7300

#Unit 6. System Physiology – Plant

Crassulacean acid metabolism (CAM). Temporal separation of CO2 uptake from photosynthetic reactions: CO2 uptake and fixation take place at night, and decarboxylation and refixation of the internally released CO2 occur during the day. The adaptive advantage of CAM is the reduction of water loss by transpiration, achieved by the stomatal opening during the night.

TLS Online TPP Program

#Id: 7301

#Unit 6. System Physiology – Plant

Typically, a CAM plant loses 50 to 100 g of water for every gram of CO2 gained, compared with values of 250 to 300 g and 400 to 500 g for C4 and C3 plants Thus, CAM plants have a competitive advantage in dry environments.

TLS Online TPP Program

#Id: 7302

#Unit 6. System Physiology – Plant

In CAM plants, formation of the C4 acids is both temporally and spatially separated. At night, CO2 is captured by PEP carboxylase in the cytosol, and the malate that forms from the oxaloacetate product is stored in the vacuole

TLS Online TPP Program

#Id: 7303

#Unit 6. System Physiology – Plant

PEPCase‐kinase transcripts accumulate during the night, controlled by the circadian oscillator and metabolites. Nocturnal phosphorylation of PEPCase controls primary carboxylation.