LMU researchers show that certain cell organelles can efficiently compensate for mistranslated proteins – a possible key to their acclimation to environmental stress.

The precise synthesis of proteins is considered essential for cellular function. Now, a team led by LMU biologists Dr. Benjamin Brandt and Professor Hans-Henning Kunz has demonstrated for the first time that plants can cope with mistranslations during protein synthesis far more robustly than other organisms studied to date. Using the model organism Arabidopsis thaliana, the researchers showed that mitochondria and chloroplasts – the organelles crucial for energy balance and photosynthesis – can tolerate even high error rates and thus respond flexibly to mistranslations.
For their study, the researchers generated plants in which protein synthesis in organelles is more error-prone. They achieved this by means of manipulated transfer RNAs (tRNAs) that incorporate higher amounts of incorrect amino acids into proteins – a process known as mistranslation. “This allowed us, for the first time, to systematically observe how organelles deal with errors,” explains Dr. Benjamin Brandt, lead author of the study.

Different responses in chloroplasts and mitochondria

Their results revealed that the two organelles respond in strikingly different ways: Mitochondria strongly suppress such errors by recognizing and rejecting these mischarged tRNAs. Chloroplasts, by contrast, tolerate some of the highest rates of certain mistranslations measured in any organism to date. Nevertheless, they possess effective compensation mechanisms that enable them to maintain their function despite mistranslated proteins.
Furthermore, the researchers observed that similar errors also occur in unmodified plants when they acclimate to temperature stress. According to the authors, this suggests that mistranslation might not merely be a random error, but could be part of a natural stress response in plants. A comparison with bacteria furnishes additional clues: It is known that controlled mistranslation under stress conditions (such as heat) can enhance survival of microorganisms.
These findings now provide a foundation for testing whether plants use similar strategies. “In the long term, this knowledge could provide scientists with new avenues to design more robust crop plants that better withstand heat, cold, and other stress conditions,” says Kunz.