An XAS investigation of the nickel site structure in the transcriptional regulator InrS

J Inorg Biochem. 2017 Dec:177:352-358. doi: 10.1016/j.jinorgbio.2017.08.003. Epub 2017 Aug 10.

Abstract

InrS (Internal nickel-responsive Sensor) is a transcriptional repressor of the nickel exporter NrsD and de-represses expression of the exporter upon binding Ni(II) ions. Although a crystal structure of apo-InrS has been reported, no structure of the protein with metal ions bound is available. Herein we report the results of metal site structural investigations of Ni(II) and Cu(II) complexes of InrS using X-ray absorption spectroscopy (XAS) that are complementary to data available from the apo-InrS crystal structure, and are consistent with a planar four-coordinate [Ni(His)2(Cys)2] structure, where the ligands are derived from the side chains of His21, Cys53, His78, and Cys82. Coordination of Cu(II) to InrS forms a nearly identical planar four-coordinate complex that is consistent with a simple replacement of the Ni(II) center by Cu(II).

Keywords: EXAFS; InrS; Metalloregulator; Nickel; XAS.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Ligands
  • Molecular Structure
  • Nickel / chemistry
  • Nickel / metabolism*
  • Protein Binding
  • Repressor Proteins / chemistry
  • Repressor Proteins / metabolism*
  • Synechocystis
  • X-Ray Absorption Spectroscopy

Substances

  • Bacterial Proteins
  • Ligands
  • Repressor Proteins
  • Nickel