Download MendeleyAllosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin.
Knapp, J.E., Pahl, R., Srajer, V., Royer Jr., W.E.(2006) Proc Natl Acad Sci U S A 103: 7649-7654
- PubMed: 16684887
- DOI: https://doi.org/10.1073/pnas.0509411103
- Primary Citation of Related Structures:
2GRF, 2GRH, 2GRZ - PubMed Abstract:
Protein allostery provides mechanisms for regulation of biological function at the molecular level. We present here an investigation of global, ligand-induced allosteric transition in a protein by time-resolved x-ray diffraction. The study provides a view of structural changes in single crystals of Scapharca dimeric hemoglobin as they proceed in real time, from 5 ns to 80 micros after ligand photodissociation. A tertiary intermediate structure forms rapidly (<5 ns) as the protein responds to the presence of an unliganded heme within each R-state protein subunit, with key structural changes observed in the heme groups, neighboring residues, and interface water molecules. This intermediate lays a foundation for the concerted tertiary and quaternary structural changes that occur on a microsecond time scale and are associated with the transition to a low-affinity T-state structure. Reversal of these changes shows a considerable lag as a T-like structure persists well after ligand rebinding, suggesting a slow T-to-R transition.
Organizational Affiliation:
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
