Download MendeleyStructural basis for the root effect in haemoglobin.
Mylvaganam, S.E., Bonaventura, C., Bonaventura, J., Getzoff, E.D.(1996) Nat Struct Biol 3: 275-283
- PubMed: 8605630
- DOI: https://doi.org/10.1038/nsb0396-275
- Primary Citation of Related Structures:
1SPG - PubMed Abstract:
The remarkable ability of root effect haemoglobins to pump oxygen against high O2 gradients results from extreme, acid-induced reductions in O2 affinity and cooperativity. The long-sought mechanism for the root effect, revealed by the 2 angstrom crystal structure of the ligand-bound haemoglobin from Leiostomus xanthurus at pH 7.5, unexpectedly involves modulation of the R-state. Key residues strategically assemble positive-charge clusters across the allosteric beta1 beta2-interface in the R-state. At low pH, protonation of the beta N terminus and His 147(HC3)beta within these clusters is postulated to destabilize the R-state and promote the acid-triggered, allosteric R-->T switch with concomitant O2 release. Surprisingly, a set of residues specific to root effect haemoglobins recruit additional residues, conserved among most haemoglobins, to produce the root effect.
Organizational Affiliation:
The Scripps Research Institute, La Jolla, California 92037, USA.
