James N. Siedow
Professor and Vice Provost for Research

681-6438

119 Allen Bldg.

Research Interests: Function and regulation of plant respiratory pathways

Physiological, biochemical and molecular studies of plant oxidative processes.

Research in my laboratory studies metabolic processes related to aerobic respiration in plants and fungi. Specifically, this research involves isolating and characterizing the structural and regulatory features of the cyanide-resistant "alternative" oxidase associated with all plant and many fungal mitochondria. The mechanism of action of a regulatory sulfhydryl-disulfide system on the alternative oxidase and its interplay with the activating effects of alpha-keto acids are currently under study, as is the characterization of structural features of the alternative protein and its active site.

Comparative studies of the plant and fungal alternative oxidases have indicated a common structural framework but distinctly different regulatory features. This research involves the application of standard biochemical approaches, including chemical cross-linking, immunochemical technologies, and electrochemical methodologies. These approaches are further complemented by the use of site-directed mutagenesis of the alternative oxidase expressed in both the bacterium E. coli and transgenic Arabidopsis thaliana.

Transformed Arabidopsis having over- and underexpressed wild-type, as well as altered forms of the alternative oxidase lacking normal regulatory control have been developed and are being used to characterize the role played by the alternative oxidase in response to different developmental and environmental circumstances, including extremes of temperature, pathogen infection, and nutrient limitations.

Current projects: Cyanide-resistant respiration and plant stress

Recent Publications   (More Publications)   (search)

1. A.L. Umbach, V.S. Ng, J.N. Siedow, A tale of two cysteines, Biochim. Biophys. Acta, vol. 1757 (2006), pp. 135-142 .
2. D.M. Rhoads, A.L. Umbach, S.C. Chalivendra, J.N. Siedow, Mitochondrial reactive oxygen species: contribution to oxidative stress and inter-organellar signaling, Plant Physiol., vol. 141 (2006), pp. 357-366 .
3. A.L. Umbach, V.S. Ng and J.N. Siedow, Regulation of plant alternative oxidase activity: A tale of two cysteines, Biochim. Biophys. Acta (Accepted, 2006) .
4. D.M. Rhoads, A.L. Umbach, S.C. Chalivendra and J.N. Siedow, Mitochondiral ROS: Contribution to oxidative stress and inter-organellar signaling, Plant Physiol (Submitted, 2006) .
5. A. L. Umbach, F. Fiorani, J.N. Siedow, Characterization of transformed Arabidopsis thaliana with altered alternative oxidase levels and analysis of effects on reactive oxygen species in tissue, Plant Physiology, vol. 139 (2005), pp. 1806-1820 .