The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure

Jade B Aitken; Christopher J D Austin; Nicholas H Hunt; Helen J Ball; Peter A Lay

doi:10.1016/j.bbrc.2014.05.054

The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure

Biochem Biophys Res Commun. 2014 Jul 18;450(1):25-9. doi: 10.1016/j.bbrc.2014.05.054. Epub 2014 May 22.

Authors

Jade B Aitken¹, Christopher J D Austin², Nicholas H Hunt³, Helen J Ball³, Peter A Lay⁴

Affiliations

¹ School of Chemistry, The University of Sydney, NSW 2006, Australia; Australian Synchrotron, Clayton, Victoria 3168, Australia; Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan.
² School of Chemistry, The University of Sydney, NSW 2006, Australia; Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
³ Department of Pathology and Bosch Institute, The University of Sydney, Camperdown, NSW 2006, Australia.
⁴ School of Chemistry, The University of Sydney, NSW 2006, Australia. Electronic address: peter.lay@sydney.edu.au.

PMID: 24858687
DOI: 10.1016/j.bbrc.2014.05.054

Abstract

Multiple-scattering (MS) analysis of EXAFS data on met-indoleamine 2,3-dioxygenase-2 (IDO2) and analysis of XANES have provided the first direct structural information about the axial donor ligands of the iron center for this recently discovered protein. At 10K, it exists in a low-spin bis(His) form with Fe-Np(av)=1.97Å, the Fe-NIm bond lengths of 2.11Å and 2.05Å, which is in equilibrium with a high-spin form at room temperature. The bond distances in the low-spin form are consistent with other low-spin hemeproteins, as is the XANES spectrum, which is closer to that of the low-spin met-Lb than that of the high-spin met-Mb. The potential physiological role of this spin equilibrium is discussed.

Keywords: EXAFS; Heme environment; Indoleamine 2,3-dioxygenase-2 (IDO2); Mixed-spin species; X-ray absorption fine structure.

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

Computer Simulation
Heme / chemistry*
Indoleamine-Pyrrole 2,3,-Dioxygenase / chemistry*
Indoleamine-Pyrrole 2,3,-Dioxygenase / ultrastructure*
Iron / chemistry*
Models, Chemical*
Models, Molecular*
Protein Conformation

Substances

IDO2 protein, human
Indoleamine-Pyrrole 2,3,-Dioxygenase
Heme
Iron

Grants and funding

P41RR001209/RR/NCRR NIH HHS/United States