The formation of hydrogen bond in the proximal heme pocket of HemAT-Bs upon ligand binding

Biochem Biophys Res Commun. 2007 Jun 15;357(4):1053-7. doi: 10.1016/j.bbrc.2007.04.041. Epub 2007 Apr 18.

Abstract

HemAT-Bs is the heme-based O(2) sensor responsible for aerotaxis control in Bacillus subtilis. In this study, we measured the time-resolved resonance Raman spectra of full-length HemAT-Bs wild-type (WT) and Y133F in the deoxy form and the photoproduct after photolysis of CO-bound form. In WT, the nu(Fe-His) band for the 10 ps photoproduct was observed at higher frequency by about 2 cm(-1) compared with that of the deoxy form. This frequency difference is relaxed in hundreds of picoseconds. This time-dependent frequency shift would reflect the conformational change of the protein matrix. On the other hand, Y133F mutant did not show such a substantial nu(Fe-His) frequency shift after photolysis. Since a hydrogen bond to the proximal His induces an up-shift of the nu(Fe-His) frequency, these results indicate that Tyr133 forms a hydrogen bond to the proximal His residue upon the ligand binding. We discuss a functional role of this hydrogen bond formation for the signal transduction in HemAT-Bs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / ultrastructure*
  • Binding Sites
  • Carbon Monoxide / chemistry*
  • Computer Simulation
  • Heme / chemistry*
  • Heme-Binding Proteins
  • Hemeproteins / chemistry*
  • Hemeproteins / ultrastructure*
  • Hydrogen Bonding
  • Ligands
  • Models, Chemical*
  • Models, Molecular*
  • Protein Binding
  • Protein Conformation

Substances

  • Bacterial Proteins
  • Heme-Binding Proteins
  • Hemeproteins
  • Ligands
  • heme protein, bacteria
  • Heme
  • Carbon Monoxide