Transport Proteins Enabling Plant Photorespiratory Metabolism

Abstract

Photorespiration (PR) is a metabolic repair pathway that acts in oxygenic photosynthetic organisms to degrade a toxic product of oxygen fixation generated by the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase. Within the metabolic pathway, energy is consumed and carbon dioxide released. Consequently, PR is seen as a wasteful process making it a promising target for engineering to enhance plant productivity. Transport and channel proteins connect the organelles accomplishing the PR pathway—chloroplast, peroxisome, and mitochondrion—and thus enable efficient flux of PR metabolites. Although the pathway and the enzymes catalyzing the biochemical reactions have been the focus of research for the last several decades, the knowledge about transport proteins involved in PR is still limited. This review presents a timely state of knowledge with regard to metabolite channeling in PR and the participating proteins. The significance of transporters for implementation of synthetic bypasses to PR is highlighted. As an excursion, the physiological contribution of transport proteins that are involved in C4 metabolism is discussed.

Comparative transcriptomics reveals the role of altered energy metabolism in the establishment of single-cell C4 photosynthesis in Bienertia sinuspersici

“…A BOUT DE SOUFFLE (BOU) transporter is related to the glycine dehydrogenase complex (GDC) and serine hydroxymethyltransferase (SHMT) involved in photorespiration. A recent study suggested that BOU functions as a glutamate transporter in photorespiration ( Kuhnert et al., 2021 ). BOU was found in Cluster 9 and showed an inverse relationship with the expression pattern of ASP-AT2 in Cluster 1.…”

Effects of Heat Stress on Plant-Nutrient Relations: An Update on Nutrient Uptake, Transport, and Assimilation

“…The membrane of peroxisomes primarily has two types of transporters-the pore-forming diffusion channels referred to as non-selective transporters, and carrier proteins with high specificity. The former allows the passage of small hydrophilic molecules up to 300-400 Da, such as amino acids, while the latter is primarily involved in the transport of larger molecules, such as NAD+ [134][135][136]. The current status of knowledge about the peroxisomal transport proteins is rather limited, and knowledge on their involvement and behavior in stress conditions is all the scarcer.…”

Is plastidic glutamine synthetase essential for C3 plants? A tale of photorespiratory mutants, ammonium tolerance and conifers

“…Indeed, due to the high flux of the photorespiratory route, a transporter that permits the import of photorespiratory NH 4 + into the chloroplast is likely needed. However, in spite of many efforts to identify such a transporter, it has not yet been found (Kuhnert et al ., 2021).…”