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Structure/function analysis of signal transduction proteinsThe goal of research in our laboratory is to understand the molecular mechanisms of receptor-mediated signal transduction. In particular. research is focused on elucidating structure/function relationships in proteins involved in information processing using a combination of molecular genetic. biochemical and X-ray crystallographic methods. Specific interest is directed toward investigating the role of covalent modifications of proteins in signaling pathways. A large fraction of bacterial signal transduction systems utilize a common mechanism involving transfer of a high-energy phosphoryl group from a histidine protein kinase to an aspartate residue of a response regulator protein. The regulatory domains of the response regulator proteins can be thought of as phosphorylation-activated switches that are turned on and off by phosphorylation and dephosphorylation. In the active. phosphorylated state. the conserved regulatory domains interact productively with other protein domains to activate specific effector functions such as flagellar rotation. regulation of transcription. or enzymatic catalysis. We have solved the crystal structures of several representative members of the response regulator family. These structures and correlated biochemical studies have provided insight into the mechanism of function of response regulators. Phosphorylation alters the conformation of the regulatory domain and the altered molecular surface is exploited for regulatory protein-protein interactions. Current efforts are focused on understanding the molecular details of these regulatory interactions through characterization of the active forms of these proteins in the context of protein-protein and protein-DNA complexes. Additional studies are focused on receptor modification enzymes that contribute to receptor adaptation and on characterization of a cholesterol-binding protein involved in intracellular cholesterol trafficking. Selected PublicationsMack TR, Gao R, Stock AM. (2009) Probing the roles of the two different dimers mediated by the receiver domain of the response regulator PhoB. J Mol Biol. 389(2):349-64. Guhaniyogi J, Sohar I, Das K, Stock AM, Lobel P. (2008) Crystal structure and autoactivation pathway of the precursor form of human tripeptidyl-peptidase 1, the enzyme deficient in late infantile ceroid lipofuscinosis. J Biol Chem. 284(6):3985-97. Gao R, Tao Y, Stock AM. (2008) System-level mapping of Escherichia coli response regulator dimerization with FRET hybrids. Mol Microbiol. 69(6):1358-72. Sidote DJ, Barbieri CM, Wu T, Stock AM. (2008) Structure of the Staphylococcus aureus AgrA LytTR domain bound to DNA reveals a beta fold with an unusual mode of binding. Structure. 16(5):727-35. Barbieri CM, Stock AM. (2008) Universally applicable methods for monitoring response regulator aspartate phosphorylation both in vitro and in vivo using Phos-tag-based reagents. Anal Biochem. 376(1):73-82. Guhaniyogi J, Wu T, Patel SS, Stock AM. (2008) Interaction of CheY with the C-terminal peptide of CheZ. J Bacteriol. 190(4):1419-28. Dixit SS, Sleat DE, Stock AM, Lobel P. (2007) Do mammalian NPC1 and NPC2 play a role in intestinal cholesterol absorption? Biochem J. 408(1):1-5. Xu S, Benoff B, Liou HL, Lobel P, Stock AM. (2007) Structural basis of sterol binding by NPC2, a lysosomal protein deficient in Niemann-Pick type C2 disease. J Biol Chem. 282(32):23525-31. Bachhawat P, Stock AM. (2007) Crystal structures of the receiver domain of the response regulator PhoP from Escherichia coli in the absence and presence of the phosphoryl analog beryllofluoride. J Bacteriol. 189(16):5987-95. Friedland N, Mack TR, Yu M, Hung LW, Terwilliger TC, Waldo GS, Stock AM. (2007) Domain orientation in the inactive response regulator Mycobacterium tuberculosis MtrA provides a barrier to activation. Biochemistry. 46(23):6733-43. Gao R, Mack TR, Stock AM. (2007) Bacterial response regulators: versatile regulatory strategies from common domains. Trends Biochem Sci. 32(5):225-34. Perez E, Stock AM. (2007) Characterization of the Thermotoga maritima chemotaxis methylation system that lacks pentapeptide-dependent methyltransferase CheR:MCP tethering. Mol Microbiol. 63(2):363-78. Stock AM, Guhaniyogi J. (2006) A new perspective on response regulator activation. J Bacteriol. 188(21):7328-30. Stock AM. (2006) Transmembrane signaling by asymmetry. Nat Struct Mol Biol. 13(10):862-3. Liou HL, Dixit SS, Xu S, Tint GS, Stock AM, Lobel P. (2006) NPC2, the protein deficient in Niemann-Pick C2 disease, consists of multiple glycoforms that bind a variety of sterols. Perez E. Zheng H. Stock AM. (2006) Identification of methylation sites in Thermotoga maritima chemotaxis receptors. J Bacteriol. 188(11):4093-100. Guhaniyogi J. Robinson VL. Stock AM. (2006) Crystal structures of beryllium fluoride-free and beryllium fluoride-bound CheY in complex with the conserved C-terminal peptide of CheZ reveal dual binding modes specific to CheY conformation. J Mol Biol. 359(3):624-45. Toro-Roman A. Wu T. Stock AM. (2005) A common dimerization interface in bacterial response regulators KdpE and TorR. Protein Sci. 14(12):3077-88. Bachhawat. P. Swapna. G.V.T.. and Stock. A.M. (2005). Mechanism of activation for transcription factor PhoB suggested by different modes of dimerization in the inactive and active states. Structure. 13(9):1353-63. Toro-Roman A.. Mack. T.R. and Stock. A.M. (2005). Structural analysis and solution studies of the activated regulatory domain of the response regulator ArcA: a symmetric dimer mediated by the alpha4-beta5-alpha5 face. J. Mol. Biol. 349: 11-26. Perez. E.. West. A.H.. Stock. A.M. and Djordjevic. S. (2004). Discrimination between different methylation states of chemotaxis receptor Tar by receptor methyltransferase CheR. Biochemistry 45: 953-961. Robinson. V.L.. Wu. T. and Stock. A.M. (2003). Structural analysis of the domain interface in DrrB. a response regulator of the OmpR/PhoB subfamily. J. Bacteriol. 185:4186-4194. Friedland. N.. Liou. H.-L.. Lobel. P. and Stock. A.M. (2003). Structure of a cholesterol-binding protein deficient in Niemann-Pick type C2 disease. Proc. Natl. Acad. Sci. USA 100:2512-2517. Bourret. R.B. and Stock. A.M. (2002). Molecular information processing: lessons from bacterial chemotaxis. J. Biol. Chem. 277:9625-9628. |
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