EFFECTS OF ZINC-DEFICIENCY ON PEPTIDE-SYNTHESIS IN CULTURED TOBACCO PLANT-CELLS

To analyze the effects of Zn deficiency on protein synthesis at the tr anslation and transcription levels, proteins and peptides extracted fr om tobacco cells cultured with (+Zn) and without Zn (-Zn) were compare d by two-dimensional electrophoresis. mRNAs were compared by in vitro translation. Although the spots of translated peptides were almost ide ntical for the -Zn and +Zn treatments, one peptide spot at pI 6.0 appe ared densely by the -Zn treatment. Clear differences were observed in the separation patterns of water soluble cellular proteins and peptide s. In the -Zn treatment, two peptides at pI 4.5 (MW 45,000) and at pl 5.5 (MW 50,000) which were present in the +Zn treatment disappeared wh ile one appeared at pI 6.0 (MW 28,000). Zinc may participate in the fo rmation of some peptides and under Zn deficiency, the transcription of one mRNA for a peptide which appeared at pI 6.0 was enhanced in this study.