A Novel Haem-binding Interface in the 22 kDa Haem-binding Protein p22HBP.
Gell, D.A., Westman, B.J., Gorman, D., Liew, C.K., Welch, J.J., Weiss, M.J., Mackay, J.P.(2006) J Mol Biology 362: 287-297
- PubMed: 16905148 
- DOI: https://doi.org/10.1016/j.jmb.2006.07.010
- Primary Citation of Related Structures:  
2HVA - PubMed Abstract: 
The 22 kDa haem-binding protein, p22HBP, is highly expressed in erythropoietic tissues and binds to a range of metallo- and non-metalloporphyrin molecules with similar affinities, suggesting a role in haem regulation or synthesis. We have determined the three-dimensional solution structure of p22HBP and mapped the porphyrin-binding site, which comprises a number of loops and a alpha-helix all located on a single face of the molecule. The structure of p22HBP is related to the bacterial multi-drug resistance protein BmrR, and is the first protein with this fold to be identified in eukaryotes. Strikingly, the porphyrin-binding site in p22HBP is located in a similar position to the drug-binding site of BmrR. These similarities suggest that the broad ligand specificity observed for both BmrR and p22HBP may result from a conserved ligand interaction mechanism. Taken together, these data suggest that the both the fold and its associated function, that of binding to a broad range of small hydrophobic molecules, are ancient, and have been adapted throughout evolution for a variety of purposes.
Organizational Affiliation: 
School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia. dagell@usyd.edu.au