Plant cytoplasmic GAPDH: redox post-translational modifications and moonlighting properties

Area of Science:

• Biochemistry
• Plant Biology
• Molecular Biology

Background:

• Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key glycolytic enzyme with known non-metabolic functions in animal cells, regulated by redox post-translational modifications.
• Plant GAPDH isoforms exist in cytoplasm and plastids, participating in glycolysis and the Calvin-Benson cycle, with a sensitive active site cysteine prone to oxidative modification.
• While animal GAPDH's multifunctionality is established, non-metabolic roles in plants remain largely unexplored.

Purpose of the Study:

• To review the molecular mechanisms of redox regulation in plant cytoplasmic GAPDH, considering its crystal structure.
• To inventory the known redox-dependent functions of animal GAPDH.
• To explore the emerging roles of oxidatively modified GAPDH in plant stress signaling pathways.

Main Methods:

• Literature review focusing on crystal structure analysis of plant GAPDH.
• Compilation of known redox-dependent functions in animal GAPDH.
• Analysis of studies investigating plant GAPDH modifications and stress responses.

Main Results:

• Plant cytoplasmic GAPDH, like its animal counterpart, is susceptible to redox modifications (e.g., glutathionylation, S-nitrosylation) at its active site cysteine.
• These modifications can inhibit catalytic activity but may enable alternative, non-metabolic functions in plants.
• Studies in Arabidopsis demonstrate the utility of oxidatively modified GAPDH in understanding redox regulatory networks involving glutathione and thioredoxins.

Conclusions:

• Redox post-translational modifications are crucial for regulating plant cytoplasmic GAPDH's catalytic activity and subcellular localization.
• Plant GAPDH may possess "moonlighting" functions, similar to animal GAPDH, triggered by oxidative stress.
• Further research into oxidatively modified plant GAPDH is essential for understanding its role in stress signaling and cellular regulation.