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Modeling the ComD/ComE/comcde interaction network using small angle X-ray scattering.

Dyana Sanchez1, Marion Boudes, Herman van Tilbeurgh

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|February 24, 2015
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Summary
This summary is machine-generated.

Phosphorylation regulates Streptococcus pneumoniae competence by altering ComE protein structure. This structural change affects DNA binding and promoter bending, controlling gene expression and the competence state.

Keywords:
ComD-ComE two-component systemDNA-protein complexesStreptococcus pneumoniaecompetencesmall-angle X-ray scattering

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Area of Science:

  • Molecular Biology
  • Microbiology
  • Structural Biology

Background:

  • The ComD-ComE two-component system regulates competence in Streptococcus pneumoniae.
  • ComE protein exists in monomeric and dimeric states, influenced by phosphorylation.
  • Previous studies characterized ComE mutants affecting phosphorylation and dimerization.

Purpose of the Study:

  • To investigate the binding interactions between ComD, ComE, and the comcde promoter region.
  • To elucidate the structural mechanisms underlying ComE regulation of competence.
  • To analyze the role of ComE oligomerization and DNA bending in gene regulation.

Main Methods:

  • Small-angle X-ray scattering (SAXS) was used to study protein-DNA complexes.
  • Molecular modeling was employed to interpret SAXS data and generate structural models.
  • SAXS data and models were deposited in the Small Angle Scattering Biological Data Bank (SASBDB).

Main Results:

  • ComD catalytic domain dimer binds two ComE monomers, positioning key residues for phosphorylation.
  • ComE(58E) mutant forms a compact dimer with comcde, similar to crystal structures.
  • ComE(58A) mutant exhibits multiple conformations with comcde, with or without dimer contacts.
  • Different ComE oligomeric states induce varying degrees of promoter bending.

Conclusions:

  • Phosphorylation of ComE induces DNA bending, activating the competence state.
  • Disruption of ComE dimers releases DNA bending strain, signaling the shut-off of competence.
  • Oligomeric state and DNA bending by ComE provide a mechanism for competence regulation.