Effector-induced self-association and conformational changes in the enhancer-binding protein NTRC

Molecular Microbiology
M E Farez-VidalR Dixon

Abstract

The Klebsiella pneumoniae nitrogen regulatory protein NTRC is a response regulator which activates transcription in response to nitrogen limitation, and is a member of the family of sigma N-dependent enhancer-binding proteins. Using limited trypsin digestion, two domains of NTRC were detected and conformational changes within the protein in response to the binding of ligands were also observed. In the absence of ligands, the major digestion products were 42, 36 and 12.5 kDa bands corresponding to the central plus C-terminal domain, the central domain, and the N-terminal domains, respectively. Upon binding of purine but not pyrimidine nucleotides, the 36 kDa band was insensitive to further proteolysis, indicative of a conformational change in the central domain. Analysis of the dependence of this insensitivity on ATP gamma S concentration suggested an apparent dissociation constant (Kd) for ATP gamma S of 150 microM. In the presence of DNA, both the central and C-terminal domains of NTRC were insensitive to proteolytic cleavage, indicative of a further conformational change. NTRC S160F, a mutant form of NTRC that is active in the absence of phosphorylation, was more stable to proteolysis than the wild-type protein. This mutant p...Continue Reading

Citations

Apr 3, 2001·Current Opinion in Microbiology·H Xu, T R Hoover
Jun 29, 1999·Cold Spring Harbor Symposia on Quantitative Biology·I RombelS Kustu
Jun 19, 2002·Protein Science : a Publication of the Protein Society·Sarah A HobartWilfredo Colón
Aug 1, 1996·Genes to Cells : Devoted to Molecular & Cellular Mechanisms·J Pittard
Aug 16, 2002·Molecular Microbiology·X ZhangM Buck

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