We propose to continue our study of the genetics, physiology, and biochemistry of the NRI-NRII two-component signal transduction system that plays a major role in controlling nitrogen assimilation in E. coli. This system provides a paradigm for the regulation of central metabolism by signals of carbon and nitrogen status. Our work on the NRI/NRII system also provides a paradigm for understanding two-component signal transduction systems. Two component signal transduction systems are the most common type of signal transduction system in bacteria and are also present in lower eukaryotes and plants. In bacteria, these systems control the cell cycle, development, virulence, chemotaxis, numerous responses to environmental stress, and various aspects of metabolism. Our work will also provide a paradigm for signal transduction by PII proteins, which are the most widely distributed signal transduction proteins in nature, Our studies investigate how PII proteins integrate distinct signals and control receptors that are signal-transduction enzymes. Thus, the proposed research will directly investigate signal transduction mechanisms that are widely-occuring in nature and have significant impact on human health and well-being. The proposed work will focus on structure/function studies of the NRI and NRII proteins of E. coli. The approaches use a variety of genetic, biochemical, and biophysical methods and are designed to provide detailed information on the mechanisms of regulation.
The Specific Aims i nclude: (1) Determining the mechanism of regulation of NRII kinase and phosphatase activities by Pll, and (2) Determining the mechanism of the NRI """"""""autophosphatase"""""""" activity, and its control by the complex of NRII and Pll. In both Specific Aims, biochemical approaches are used to identify interacting surfaces of the signalling proteins, the chemistry of the activities, and the interactions of protein domains that result in regulation of the catalytic activities. Genetic approaches are used to define the functions of the proteins, and map specific functions to regions of proteins. Biophysical approaches are used to determine the structures of proteins. Given their widespread occurance in nature and direct link to numerous public health and agricultural issues, understanding the mechanisms of signal transduction used by two-component systems and Pll signalling proteins is an important objective. Our studies with a model system should allow rapid progress. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM059637-06
Application #
7172959
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Shapiro, Bert I
Project Start
2001-04-01
Project End
2010-01-31
Budget Start
2007-02-01
Budget End
2008-01-31
Support Year
6
Fiscal Year
2007
Total Cost
$301,088
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biochemistry
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Jiang, Peng; Ninfa, Alexander J (2011) A source of ultrasensitivity in the glutamine response of the bicyclic cascade system controlling glutamine synthetase adenylylation state and activity in Escherichia coli. Biochemistry 50:10929-40
Jiang, Peng; Ventura, Alejandra C; Sontag, Eduardo D et al. (2011) Load-induced modulation of signal transduction networks. Sci Signal 4:ra67
Ninfa, Alexander J (2010) Use of two-component signal transduction systems in the construction of synthetic genetic networks. Curr Opin Microbiol 13:240-5
Ventura, Alejandra C; Jiang, Peng; Van Wassenhove, Lauren et al. (2010) Signaling properties of a covalent modification cycle are altered by a downstream target. Proc Natl Acad Sci U S A 107:10032-7
Jiang, Peng; Ninfa, Alexander J (2009) Sensation and signaling of alpha-ketoglutarate and adenylylate energy charge by the Escherichia coli PII signal transduction protein require cooperation of the three ligand-binding sites within the PII trimer. Biochemistry 48:11522-31
Jiang, Peng; Ninfa, Alexander J (2009) Alpha-ketoglutarate controls the ability of the Escherichia coli PII signal transduction protein to regulate the activities of NRII (NrB but does not control the binding of PII to NRII. Biochemistry 48:11514-21
Jiang, Peng; Ninfa, Alexander J (2007) Escherichia coli PII signal transduction protein controlling nitrogen assimilation acts as a sensor of adenylate energy charge in vitro. Biochemistry 46:12979-96
Jiang, Peng; Mayo, Avraham E; Ninfa, Alexander J (2007) Escherichia coli glutamine synthetase adenylyltransferase (ATase, EC 2.7.7.49): kinetic characterization of regulation by PII, PII-UMP, glutamine, and alpha-ketoglutarate. Biochemistry 46:4133-46
Jiang, Peng; Pioszak, Augen A; Ninfa, Alexander J (2007) Structure-function analysis of glutamine synthetase adenylyltransferase (ATase, EC 2.7.7.49) of Escherichia coli. Biochemistry 46:4117-32
Ninfa, Alexander J (2007) Regulation of carbon and nitrogen metabolism: adding regulation of ion channels and another second messenger to the mix. Proc Natl Acad Sci U S A 104:4243-4

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