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item Huber, Steven
item Hardin, Shane

Submitted to: Current Opinion in Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2004
Publication Date: 6/1/2004
Citation: Huber, S.C., Hardin, S.C. 2004. Numerous post-translational modifications provide opportunites for the intricate regulation of metabolic enzymes at multiple levels. Plant Biology. 7:318-322.

Interpretive Summary: Full understanding of the control of plant carbon and nitrogen metabolism involves knowledge of all the biological mechanisms that determine the cellular and subcellular content of each protein as well as their enzymatic activity. One major way in which enzyme activity can be regulated involves post-translational modification of the protein. In eukaryotes, there are many post-translational modifications of proteins that have been described and involve covalent processing events that alter the protein either by proteolytic cleavage or modification of a specific amino acid. While many different modifications are known to occur, those that are readily reversible are of most relevance to the regulation of metabolism. Recent results suggest that important mechanisms in plants include reversible Ser/Thr-phosphorylation, O-glycosylation, redox modulation of thiol/disulfide bonds, and a newly emerging thiol-redox mechanism that involves nitric oxide as an endogenous thiol-reactive molecule in a process known as S-nitrosylation. These modifications are all reversible, highly specific, and can potentially affect the target protein in many different ways. This information will be of broad interest to plant scientists, as post-translational modifications are recognized to be an important facet of functional genomics. In particular, we draw attention to several modifications that are not well understood in plants but are predicted to be important in plant perception, and response to, nitrogen. Identifying important regulatory mechanisms controlling the activities of key plant enzymes is necessary in order to devise rationale approaches to control plant metabolism.

Technical Abstract: The metabolic plasticity displayed by plants during normal development, and in response to environmental fluctuations and stressors, is essential for their growth and survival. The capacity to intricately regulate metabolic enzymes arises in part from post-translational modifications that can affect enzymatic activity, intracellular localization, protein-protein interactions, and stability. Protein phosphorylation and thiol/disulfide redox modulation are modifications that are known to be important in plants, and it is likely that O-glycosylation and S-nitrosylation will emerge as important mechanisms in the future. Recent advances in the field of proteomics, in particular the development of novel and specific chemistries for detection of a diverse number of modifications, is rapidly expanding our awareness of possible modifications and our understanding of enzymes whose function is likely to be regulated post-translationally.