DBG's Eduard Strasburger Workshop - Co- and posttranslational control in chloroplasts

The development and operation of chloroplasts (or other members of the plastid family of plant organelles) requires the participation of thousands of different organellar proteins. Most chloroplast proteins are nucleus-encoded and synthesized in the cytosol in precursor form. These preproteins pass through multiprotein import machines in the organelle’s outer and inner envelope membranes –...

Chloroplast-encoded multi-span thylakoid membrane proteins are crucial for photosynthetic complexes, yet the coordination of their biogenesis remains poorly understood. To identify factors that specifically support the cotranslational biogenesis of the reaction center protein D1 of photosystem (PS) II, we generated and affinity-purified stalled ribosome-nascent chain complexes (RNCs) bearing...

Chloroplasts, crucial organelles in autotrophic organisms, possess distinctive regulatory pathways to control molecular processes that respond dynamically to environmental cues. Protein synthesis in these organelles relies on transfer RNAs (tRNAs) encoded by the chloroplast genome, which undergo extensive post-transcriptional modifications. These modifications play critical roles in accurate...

Accurate protein translation is a hallmark for cell function. It guarantees an efficient proteome while minimizing detrimental unfolded proteins and concomitant energy loss. Surprisingly, protein mistranslation happens quite frequently in vivo (error rates 10-2 to 10-4) mainly due to transfer RNA (tRNA) mis-decoding and tRNA mis-acylation. Bacteria, mitochondria and plastids synthesize...

The N-termini of chloroplast proteins are a common site of co- and post-translational protein modifications, including N-terminal acetylation, transit peptide cleavage and subsequent proteolytic processing, that result in distinct proteoforms that may differ in activity, interactions and location. However, protein N-terminal peptides are often missed in standard shotgun proteomics...

Cysteine redox modulation in proteins is a reversible adaptation to changing environments. For example, activity adjustment of the chloroplast ATP synthase (CF1FO) ensure full activity in the light and deactivation during night. The latter is believed to prevent ATP hydrolysis and build-up of excessive proton motive force (pmf). The adjustment is realised by a cysteine couple in the central...

Photosynthesis must be dynamically regulated in response to environmental conditions to prevent photoinhibition and photodamage to the photosystems. Various post-translational modifications of proteins are known to play important roles in modulating photosynthetic efficiency during plant acclimation responses. Alongside phosphorylation and dithiol-based modifications, acetylation of amino...