Intrinsically Disordered Bacterial Polar Organizing Protein Z, PopZ, Interacts with Protein Binding Partners Through an N-terminal Molecular Recognition Feature.

Academic Article


  • The polar organizing protein Z (PopZ) is necessary for the formation of three-dimensional microdomains at the cell poles in Caulobacter crescentus, where it functions as a hub protein that recruits multiple regulatory proteins from the cytoplasm. Although a large portion of the protein is predicted to be natively unstructured, in reconstituted systems PopZ can self-assemble into a macromolecular scaffold that directly binds to at least ten different proteins. Here we report the solution NMR structure of PopZΔ134-177, a truncated form of PopZ that does not self-assemble but retains the ability to interact with heterologous proteins. We show that the unbound form of PopZΔ134-177 is unstructured in solution, with the exception of a small amphipathic α-helix in residues M10-I17, which is included within a highly conserved region near the N-terminal. In applying NMR techniques to map the interactions between PopZΔ134-177 and one of its binding partners, RcdA, we find evidence that the α-helix and adjoining amino acids extending to position E23 serve as the core of the binding motif. Consistent with this, a point mutation at position I17 severely compromises binding. Our results show that a partially structured Molecular Recognition Feature (MoRF) within an intrinsically disordered domain of PopZ contributes to the assembly of polar microdomains, revealing a structural basis for complex network assembly in Alphaproteobacteria that is analogous to those formed by intrinsically disordered hub proteins in other kingdoms.
  • Authors

  • Nordyke, Christopher T
  • Ahmed, Yasin M
  • Puterbaugh, Ryan Z
  • Bowman, Grant R
  • Varga, Krisztina
  • Status

    Publication Date

  • November 20, 2020
  • Published In


  • Bacterial Proteins
  • Blood Proteins
  • Caulobacter crescentus
  • Chromosomes, Bacterial
  • Intrinsically Disordered Proteins
  • NMR spectroscopy
  • Nuclear Magnetic Resonance, Biomolecular
  • PopZ
  • Protein Binding
  • Protein Conformation
  • Protein Multimerization
  • hub protein
  • intrinsic disorder
  • molecular recognition feature
  • Digital Object Identifier (doi)

    Start Page

  • 6092
  • End Page

  • 6107
  • Volume

  • 432
  • Issue

  • 23