Sulfitolysis and thioredoxin-dependent reduction reveal the presence of a structural disulfide bridge in spinach chloroplast fructose-1,6-bisphosphatase

AbstractA significant difference between cytosolic and chloroplastic fructose-1,6-bisphosphatase (FbPase) is an extra peptide in the middle of chloroplast FbPase which contains three additional cysteine residues. Sit-directed mutagenesis experiments have shown that at least two of these cysteine residues are involved in forming the regulatory disulfide bridge [Jacquot, J.-P. et al., FEBS Lett. 401 (1997) 143–147] which is the presupposition for the thioredoxin-dependent control of chloroplast FbPase activity. Here we report that each subunit of the FbPase contains an additional structural disulfide bridge which has been observed by combined application of thioredoxins and sulfitolysis. Observation of the structural disulfide bridges by sulfitolysis was only possible when the FbPase was already specifically reduced by the homologous thioredoxin species TRm and TRf from spinach chloroplasts. Interestingly, the accessibility of the structural disulfide bridge for sulfite ions depends on the thioredoxin species engaged in the thioredoxin/FbPase complex

Novel thioredoxin targets in Dictyostelium discoideum identified by two-hybrid analysis: interactions of thioredoxin with elongation factor 1 α and yeast alcohol dehydrogenase

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich. - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively

Redox control of hydrogenase activity in the green alga Scenedesmus obliquus by thioredoxin and other thiols

AbstractThe activity of the NiFe-hydrogenase from the green alga Scenedesmus obliquus is inhibited by both algal thioredoxins f and I+II, and by Escherichia coli thioredoxin. The strongest inhibition was observed with homologous chloroplastic thioredoxin f (I50=21 nM) and E. coli thioredoxin (I50=83 nM). For the homologous cytoplasmic thioredoxins I+II an I50 of 667 nM was determined. Glutathione shows a similar but much less pronounced inhibitory effect whereas dithiothreitol had no effect. In addition to glucose-6-phosphate dehydrogenase, NiFe-hydrogenase is only the second enzyme known to be inhibited by reduced thioredoxin