Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2006
Publication Date: 4/8/2006
Citation: Cheng, N-H., Liu, J-Z., Brock, A., Nelson, R.S., Hirschi, K.D. 2006. Arabidopsis PICOT1 is a chloroplastic/plastidic glutaredoxin critical for protection of cells against protein oxidative damage [abstract]. Keystone Symposia on Molecular and Cellular Biology: Plant Responses to Abiotic Stress, April 8-13, 2006, Copper Mountain, Colorado. A109, p. 47. Interpretive Summary:
Technical Abstract: Glutaredoxins (Grxs) are ubiquitous small heat-stable oxidoreductases and members of the thioredoxin (Trx) fold protein family. In bacterial, yeast, and mammalian cells, Grxs appear to be involved in maintaining cellular redox homeostasis. However, in plants, none of Grxs has been functionally characterized. Recently, an emerging subgroup of Grxs contains a PICOT-HD (protein kinase C interacting cousin of thioredoxin homology domain) that may be critical in response to oxidative stresses. Here we demonstrate that the first plant PICOT, AtPICOT1, is a chloroplast/plastid-localized glutaredoxin. In a yeast assay, AtPICOT1 can suppress the sensitivity of yeast monothiol glutaredoxin deficient cells to HO. Mutation of an evolutionarily conserved cysteine residue within the PICOT-HD drastically affects protein stability and biological function. "In planta, AtPICOT1" expression peaked in young cotyledons, and later during development in both green tissues and vascular bundles. Analysis of "AtPICOT1" null alleles revealed that "atpicot1" is defective in early seedling growth under oxidative stresses. In addition, "atpicot1" displayed increased protein carbonylation in chloroplasts/plastids. Thus, this work describes the functional characterization of a plant PICOT-HD containing Grx and suggests a conserved biological function among PICOTs in protecting cells from protein oxidative damage and adapting organisms to external stresses.