Turning the Knobs: The Impact of Post-translational Modifications on Carbon Metabolism

Abstract

Plants rely on the carbon fixed by photosynthesis into sugars to grow and reproduce. However, plants often face non-ideal conditions caused by biotic and abiotic stresses. These constraints impose challenges to managing sugars, the most valuable plant asset. Hence, the precise management of sugars is crucial to avoid starvation under adverse conditions and sustain growth. This review explores the role of post-translational modifications (PTMs) in the modulation of carbon metabolism. PTMs consist of chemical modifications of proteins that change protein properties, including protein-protein interaction preferences, enzymatic activity, stability, and subcellular localization. We provide a holistic view of how PTMs tune resource distribution among different physiological processes to optimize plant fitness.

Regulation of Rubisco activity in crops

“…Several PTMs have been reported to target Rubisco large (RbcL) and/or small (RbcS) subunits in crops (Houtz et al ., 2008; Lehtimäki et al ., 2015; Matiolli et al ., 2022; Supporting Information Tables S1–S3). Intriguing PTMs such as RbcL Lys 14 trimethylation by the highly conserved Rubisco large subunit methyltransferase (LSMT) have been described in several Fabaceae, Solanaceae, and Cucurbitaceae species (Houtz et al ., 1992).…”

“…3), the inactivation of Rca in the dark by phosphorylation appears specific to Arabidopsis. Together with redox regulation and chloroplast energetic status, phosphorylation of Rca by the plastid-targeted casein kinase 2 (cpCK2a) at Threonine 78 (Thr 78 ) in Arabidopsis has been associated with Rca inactivation in the dark and consequent decrease in Rubisco carbamylation (Boex-Fontvieille et al, 2014;Matiolli et al, 2022). This PTM does not appear to be essential for Rca activity, playing a regulatory role redundant to that of redox status in Arabidopsis under normal conditions (Kim et al, 2016(Kim et al, , 2019.…”

PHR1 and PHL1 mediate rapid high-light responses and acclimation to triose phosphate oversupply

“…This necessitates an enzymatic machinery capable of coping with rapid changes in metabolic flux, as well as the containment of overexcitation-induced hazards. Both challenges are met not only by post-transcriptional regulation of enzyme activity (reviewed in König et al (2012), Matiolli et al (2022)), but also by pronounced changes in mRNA abundance that occur within 30 minutes upon an increase in irradiance (Vogel et al, 2014; Suzuki et al, 2015; Huang et al, 2019). The latter mechanism depends on fast signal transmission between the chloroplast and the nuclear transcription machinery.…”