Abstract
The effect of viral infection on the regulation of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in Nicotiana tabacum L. leaves was studied. PEPC activity was 3 times higher in infected plant leaves compared to healthy plants.
The reason for the increase of PEPC activity as a consequence of PVYNTN infection was studied. The amount of PEPC protein did not differ in control and PVYNTN-infected plants.
Changes in post-translational modification of PEPC by phosphorylation were evaluated by comparing activity of the native and the dephosphorylated enzyme. The infected plants were characterized by a higher decrease of the enzyme activity after its dephosphorylation, which indicated a higher phosphorylation level.
Immunochemical detection of phosphoproteins showed a more intensive band corresponding to PEPC from the infected material. This strengthens the hypothesis of an infection-related phosphorylation, which could be part of the plant's response to pathogen attack.