Stress conditions applied to the interpretation of translation machinery

Gene expression is regulated at the critical steps: a regulatory event occurs at the step which has a critical effect and is responsible for the limiting rate. Enzyme activity can be regulated at several different levels: transcriptional, translational or post-translational. In this review we describe (and illustrate with experimental data) plant stress which induces regulatory mechanisms at the translational and post-translational levels. We found evidence for autorepression regulatory system of ferritin biosynthesis. Based on the knowledge of the molecular mechanism of regulation, we believe that ferritin protects the environment against heavy metal ions and supplements biological system(s) with iron. The quinolizidine alkaloids' (QA) biosynthesis is lysine decarboxylase (LDC)-dependent. The available pool of LDC limits the conversion of lysine to cadaverine. The amount of LDC depends on transcriptional and translational efficiency. However, in the light of the presented data, we have evidence for a post-translational regulatory system, i.e. the activation of LDC from low to high activity enzyme through the conversion from higher to lower molecular weight form. The plant protection system is very efficient. Understanding of the defence systems such as plant response to stress, should provide us with a possibility of applying this knowledge in practice and finding novel applications.