Structure of the NPr:EINNtr Complex: Mechanism for Specificity in Paralogous Phosphotransferase Systems

Madeleine Strickland, Ann Marie Stanley, Guangshun Wang, Istvan Botos, Charles D. Schwieters, Susan K. Buchanan, Alan Peterkofsky, Nico Tjandra

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Paralogous enzymes arise from gene duplication events that confer a novel function, although it is unclear how cross-reaction between the original and duplicate protein interaction network is minimized. We investigated HPr:EIsugar and NPr:EINtr, the initial complexes of paralogous phosphorylation cascades involved in sugar import and nitrogen regulation in bacteria, respectively. Although the HPr:EIsugar interaction has been well characterized, involving multiple complexes and transient interactions, the exact nature of the NPr:EINtr complex was unknown. We set out to identify the key features of the interaction by performing binding assays and elucidating the structure of NPr in complex with the phosphorylation domain of EINtr (EINNtr), using a hybrid approach involving X-ray, homology, and sparse nuclear magnetic resonance. We found that the overall fold and active-site structure of the two complexes are conserved in order to maintain productive phosphorylation, however, the interface surface potential differs between the two complexes, which prevents cross-reaction.

Original languageEnglish (US)
Pages (from-to)2127-2137
Number of pages11
Issue number12
StatePublished - Dec 6 2016


  • Enzyme I
  • NPr
  • X-ray crystallography
  • nuclear magnetic resonance
  • phosphotransferase system
  • pseudocontact shifts
  • residual dipolar couplings
  • small-angle X-ray scattering
  • specificity
  • surface potential

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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