His-Tag-Mediated Dimerization of Chemoreceptors Leads to Assembly of Functional Nanoarrays

Biochemistry. 2017 Nov 7;56(44):5874-5885. doi: 10.1021/acs.biochem.7b00698. Epub 2017 Sep 22.

Abstract

Transmembrane chemotaxis receptors are found in bacteria in extended hexagonal arrays stabilized by the membrane and by cytosolic binding partners, the kinase CheA and coupling protein CheW. Models of array architecture and assembly propose receptors cluster into trimers of dimers that associate with one CheA dimer and two CheW monomers to form the minimal "core unit" necessary for signal transduction. Reconstructing in vitro chemoreceptor ternary complexes that are homogeneous and functional and exhibit native architecture remains a challenge. Here we report that His-tag-mediated receptor dimerization with divalent metals is sufficient to drive assembly of nativelike functional arrays of a receptor cytoplasmic fragment. Our results indicate receptor dimerization initiates assembly and precedes formation of ternary complexes with partial kinase activity. Restoration of maximal kinase activity coincides with a shift to larger complexes, suggesting that kinase activity depends on interactions beyond the core unit. We hypothesize that achieving maximal activity requires building core units into hexagons and/or coalescing hexagons into the extended lattice. Overall, the minimally perturbing His-tag-mediated dimerization leads to assembly of chemoreceptor arrays with native architecture and thus serves as a powerful tool for studying the assembly and mechanism of this complex and other multiprotein complexes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacterial Proteins / metabolism
  • Chemotaxis
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / physiology
  • Histidine / chemistry*
  • Histidine Kinase / chemistry
  • Histidine Kinase / physiology
  • Methyl-Accepting Chemotaxis Proteins / chemistry
  • Methyl-Accepting Chemotaxis Proteins / physiology
  • Models, Molecular
  • Multiprotein Complexes / chemical synthesis*
  • Oligopeptides / chemistry*
  • Protein Binding
  • Protein Multimerization*
  • Receptors, Cell Surface / chemistry*
  • Signal Transduction

Substances

  • Bacterial Proteins
  • CheW protein, E coli
  • Escherichia coli Proteins
  • His-His-His-His-His-His
  • Methyl-Accepting Chemotaxis Proteins
  • Multiprotein Complexes
  • Oligopeptides
  • Receptors, Cell Surface
  • Histidine
  • Histidine Kinase
  • cheA protein, E coli