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Reactive oxygen species, ROS, are produced during normal metabolism and have been shown to accumulate in response to various stimuli, including biotic and abiotic stresses. An imbalance in the metabolism of ROS is termed oxidative stress and can eventually lead to cell death, but ROS also serve as targeted, intracellular secondary messengers with regulatory roles in photosynthesis, cellular metabolism, gene expression, and overall homeostasis. ROS-modulation of protein activity occurs by site-specific, covalent modifications of proteins, primarily on the thiol of cysteine residues, including disulfide bond formation, S-sulfenylation, S-nitrosylation, and S-glutathionylation.

While alteration of the cellular redox state can lead to changes in reversible oxidation of protein thiols, the actual number and types of these oxidative modifications in plants remains largely unknown. To this end, our laboratory is interested in the development and application of proteomic methods to identify redox-regulated proteins, characterize site-specific modifications, and determine reciprocity of oxidative PTMs across numerous pathways. Knowledge gained in this pursuit will provide key insights to aid in the development of improved photosynthetic organisms with better fitness and reliability under adverse conditions.


Smythers, A; McConnell, E; Lewis, H; Mubarek, S; Hicks, L. Photosynthetic Metabolism and Nitrogen Reshuffling Are Regulated by Reversible Cysteine Thiol Oxidation Following Nitrogen Deprivation in Chlamydomonas. Plants. 2020, 9(6), 784.  

McConnell, E; Smythers, A; Hicks, L. Maleimide-Based Chemical Proteomics for Quantitative Analysis of Cysteine Reactivity. Journal of the American Society of Mass Spectrometry 31(8), 1697 – 1705.  

Ford, M.M., Smythers, A.L., McConnell, E.W., Lowery, S.C., Kolling, D.R.J. and Hicks, L.M. (2019) Inhibition of TOR in Chlamydomonas reinhardtii Leads to Rapid Cysteine Oxidation Reflecting Sustained Physiological Changes. Cells, 8. 

McConnell, E.W., Werth, E.G. and Hicks, L.M. (2018) The Phosphorylated Redox Proteome of Chlamydomonas reinhardtii: Revealing Novel Means for Regulation of Protein Structure and Function. Redox Biology, 17, 35-46.  

Redox process diagram

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