Crystal structure and ligand binding properties of the truncated hemoglobin from Geobacillus stearothermophilus
Author
Summary, in English
A novel truncated hemoglobin has been identified in the thermophilic bacterium Geobacillus stearothermophilus (Gs-trHb). The protein has been expressed in Escherichia coli, the 3D crystal structure (at 1.5 angstrom resolution) and the ligand binding properties have been determined. The distal heme pocket displays an array of hydrogen bonding donors to the iron-bound ligands, including Tyr-B10 on one side of the heme pocket and Trp-G8 indole nitrogen on the opposite side. At variance with the highly similar Bacillus subtilis hemoglobin, Gs-trHb is dimeric both in the crystal and in solution and displays several unique structural properties. In the crystal cell, the iron-bound ligand is not homogeneously distributed within each distal site such that oxygen and an acetate anion can be resolved with relative occupancies of 50% each. Accordingly, equilibrium titrations of the oxygenated derivative in solution with acetate anion yield a partially saturated ferric acetate adduct. Moreover, the asymmetric unit contains two subunits and sedimentation velocity ultracentrifugation data confirm that the protein is dimeric. (c) 2006 Elsevier Inc. All rights reserved.
Publishing year
2007
Language
English
Pages
85-94
Publication/Series
Archives of Biochemistry and Biophysics
Volume
457
Issue
1
Document type
Journal article
Publisher
Academic Press
Topic
- Biological Sciences
Keywords
- hemoglobin structure
- heme ligand binding
- thermostable hemoglobins
- bacterial hemoglobins
- truncated hemoglobins
- Geobacillus
- stearothermophilus
Status
Published
Research group
- Microbiology Group
ISBN/ISSN/Other
- ISSN: 0003-9861