Intrinsic disorder in the partitioning protein KorB persists after co-operative complex formation with operator DNA and KorA

Research output: Contribution to journalArticle

Authors

  • Phillip Callow
  • Karthik Rajasekar
  • Peter Timmins
  • Giuliano Siligardi
  • Rohanah Hussain
  • David Scott

Colleges, School and Institutes

External organisations

  • Institut Laue-Langevin
  • Diamond Light Source
  • Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus
  • University of Nottingham

Abstract

The ParB protein, KorB, from the RK2 plasmid is required for DNA partitioning and
transcriptional repression. It acts co-operatively with other proteins, including the repressor KorA. Like many multifunctional proteins, KorB contains regions of intrinsically disordered structure, existing in a large ensemble of interconverting conformations. Using NMR spectroscopy, circular dichroism and small-angle neutron scattering, we studied KorB selectively within its binary complexes with KorA and DNA, and within the ternary KorA/KorB/DNA complex. The bound KorB protein remains disordered with a mobile C-terminal domain and no changes in the secondary structure, but increases in the radius of gyration on complex formation. Comparison of wild-type KorB with an N-terminal deletion mutant allows a model of the ensemble average distances between the domains when bound to DNA. We propose that the positive co-operativity between KorB, KorA and DNA results from conformational restriction of KorB on binding each partner, while maintaining disorder.

Details

Original languageEnglish
Pages (from-to)3121–3135
Number of pages15
JournalBiochemical Journal
Volume474
Issue number18
Early online date31 Jul 2017
Publication statusPublished - 31 Aug 2017

Keywords

  • small-angle scattering, transcription regulation, circular dichroism, intrinsically disordered proteins, protein–DNA interactions, protein–protein interactions