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Effector-induced self-association and conformational changes in the enhancer-binding protein NTRC
M E Farez-Vidal1, T J Wilson, B E Davidson
1Nitrogen Fixation Laboratory, John Innes Centre, Norwich, UK.
Molecular Microbiology
|December 1, 1996
Summary
The Klebsiella pneumoniae nitrogen regulatory protein NTRC undergoes conformational changes upon ligand binding, influencing its self-association and transcriptional activation. These ligand-induced structural shifts are crucial for NTRC
Area of Science:
- Molecular Biology
- Biochemistry
- Microbiology
Background:
- Klebsiella pneumoniae nitrogen regulatory protein NTRC is a sigma N-dependent enhancer-binding protein.
- NTRC regulates transcription in response to nitrogen limitation.
Purpose of the Study:
- To investigate the conformational changes of NTRC upon ligand binding.
- To elucidate the role of ligand-mediated self-association in NTRC activation.
Main Methods:
- Limited trypsin digestion to detect protein domains and conformational changes.
- Sedimentation equilibrium analysis to study protein self-association.
- Analysis of a mutant form of NTRC (NTRC S160F).
Main Results:
- Ligand binding (purine nucleotides) induced conformational changes in NTRC's central domain.
- DNA binding stabilized both central and C-terminal domains.
- ATP gamma S binding shifted the monomer-dimer equilibrium towards dimer formation.
- NTRC S160F exhibited increased stability and a conformation similar to DNA-bound wild-type NTRC.
- Ligand binding promoted self-association of NTRC into higher-order oligomers.
Conclusions:
- Ligand binding induces significant conformational changes in NTRC.
- Ligand-mediated self-association is a key mechanism for NTRC activation.
- These findings provide insights into the regulatory mechanisms of sigma N-dependent transcriptional regulators.