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Related Experiment Videos

Model of a LexA repressor dimer bound to recA operator.

R Chattopadhyaya1, K Ghosh, V M Namboodiri

  • 1Department of Biochemistry, Bose Institute, Calcutta, India. raja@boseinst.ernet.in

Journal of Biomolecular Structure & Dynamics
|November 23, 2000
PubMed
Summary

A 3D model of the LexA repressor bound to DNA reveals autocleavage is slow due to an activation barrier. Cleavage is triggered by pH changes or RecA, involving conformational shifts and protein-protein interactions.

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Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • The LexA repressor controls DNA repair pathways.
  • Understanding LexA's structure and function is crucial for DNA repair mechanisms.

Purpose of the Study:

  • To propose a complete 3D model for the LexA repressor dimer bound to the recA operator.
  • To investigate the mechanism of LexA autocleavage and its regulation.

Main Methods:

  • Three-dimensional modeling based on existing structures and homologous proteins.
  • Analysis of biochemical and biophysical data.
  • Computational modeling of protein-protein interactions and reaction kinetics.

Main Results:

  • A complete 3D model of the LexA repressor dimer bound to the recA operator site was proposed.

Related Experiment Videos

  • LexA autocleavage has a high activation energy barrier, with specific geometric constraints preventing reaction in the operator-bound state.
  • Cleavage is facilitated by cis-trans isomerization at Pro 87 or conformational changes upon RecA activation or pH elevation.
  • The C-domains interact, forming a new beta barrel and burying significant surface area.

    • Conclusions:

    • The proposed model provides insights into LexA-DNA binding and regulation.
    • Autocleavage regulation involves conformational changes and specific amino acid interactions.
    • Protein-protein interactions between LexA monomers play a role in its function.