Identification of potential redox-sensitive cysteines in cytosolic forms of fructosebisphosphatase and glyceraldehyde-3-phosphate dehydrogenase

Tertiary-structure modeling suggests the occurrence of disulfide bonds in the cytosolic form of fructosebisphosphatase (EC 3.1.3.11) in spinach (Spinacia oleracea L.), sugarbeet (Beta vulgaris L.) and potato (Solanum tuberosum L.). Redox modulation could then control the AMP sensitivity of fructosebisphosphatase in the cytosol, as suggested by the experiments of E. Khayat et al. (1993, Plant Physiol. 101, 57–64). Modeling also reveals two cysteine residues correctly positioned to form a disulfide bond and hence potentially redox-sensitive in the cytosolic glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) from the facultative crassulacean metabolism plant Mesembryanthemum crystallinum L.Abbreviations Cys cysteine - DTT dithiothreitolThis work was supported by NSF DCB-9018265 and US Department of Energy, Office of Health and Environmental Research, under contract W-31-109-ENG-38, and by laboratory-directed research and development funding from Argonne National Laboratory. We thank Hans J. Bohnert, University of Arizona, for providing the ice plant seeds, Xiaomu Niu and Paul M. Hasegawa, Purdue University, for providing the salt bush roots, Larry Sykora and staff at the UIC Greenhouse for cultivating the ice plants, and Christie Aljets for assistance with some of the activity determinations.