Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 8/15/2007
Publication Date: 5/1/2008
Citation: Kumaran, S., Francois, J.A., Krishnan, H.B., Jez, J. 2008. Regulatory Protein-Protein Interactions in Primary Metabolism: The Case of the Cysteine Synthase Complex. In: Khan, N.A., Singh, R.P., editors. Sulfur Assimilation and Abiotic Stress in Plants. Springer-Verlag, New York. p. 97-109. Interpretive Summary:
Technical Abstract: Sulfur is an essential nutrient for plant growth and development. In plant sulfur assimilation, cysteine biosynthesis plays a central role in fixing inorganic sulfur from the environment into the metabolic precursor for cellular thiol-containing compounds. A key regulatory feature of this process is the physical association of the two enzymes involved in cysteine biosynthesis (serine acetyltransferase, SAT, and O-acetylserine sulfhydrylase, OASS) to form the cysteine synthase complex. Physiologically, this multienzyme complex acts as a molecular sensor in a regulatory circuit that coordinates sulfur assimilation and modulates cysteine production. Here we focus on aspects of the protein-protein interactions in the plant cysteine synthase complex and how formation of the complex has been studied. In addition, we summarize the initial efforts to understand the structural, kinetic, and thermodynamic basis for association of SAT and OASS in the multienzyme assembly.