MetJ repressor interactions with DNA probed by in-cell NMR

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Characterizing macromolecules at the atomic level within living cells presents significant challenges.
• Advances in Nuclear Magnetic Resonance (NMR) instrumentation and methodologies are enabling in-cell studies.
• In-cell NMR offers potential for multidimensional spectral characterization of individual macromolecular components.

Purpose of the Study:

• To investigate the in-cell behavior and interactions of the MetJ repressor protein from Escherichia coli.
• To understand the role of genomic DNA in the cellular function of the MetJ repressor.
• To explore how in-cell NMR can provide insights into protein-DNA interactions within a cellular environment.

Main Methods:

• Utilized Nuclear Magnetic Resonance (NMR) spectroscopy for atomic-level characterization.
• Conducted comparative studies on whole cells, cell lysates, and in vitro preparations of purified MetJ repressor.
• Analyzed spectral data to identify protein-DNA interactions and conformational states.

Main Results:

• NMR data provided clear evidence of extensive, nonspecific interactions between the MetJ repressor and genomic DNA in living E. coli cells.
• These nonspecific DNA interactions were observed across whole cells, lysates, and in vitro preparations.
• The findings suggest a mechanism for efficient target sequence searching facilitated by DNA tracks.

Conclusions:

• Nonspecific DNA interactions significantly influence the behavior of the MetJ repressor within the crowded cellular environment.
• Genomic DNA acts as a track, aiding the MetJ repressor in navigating cellular obstacles to find specific target sequences.
• This DNA-mediated mechanism facilitates timely control of methionine biosynthesis gene expression by the MetJ repressor.