2uyd
From Proteopedia
Crystal structure of the SmHasA mutant H83A
Structural highlights
FunctionHASA_SERMA Can bind free heme and also acquire it from hemoglobin. Conveys heme from hemoglobin to the HasR receptor which releases it into the bacterium. HasR alone can take up heme but the synergy between HasA and HasR increases heme uptake 100-fold.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHeme carrier HasA has a unique type of histidine/tyrosine heme iron ligation in which the iron ion is in a thermally driven two spin states equilibrium. We recently suggested that the H-bonding between Tyr75 and the invariantly conserved residue His83 modulates the strength of the iron-Tyr75 bond. To unravel the role of His83, we characterize the iron ligation and the electronic properties of both wild type and H83A mutant by a variety of spectroscopic techniques. Although His83 in wild type modulates the strength of the Tyr-iron bond, its removal causes detachment of the tyrosine ligand, thus giving rise to a series of pH-dependent equilibria among species with different axial ligation. The five coordinated species detected at physiological pH may represent a possible intermediate of the heme transfer mechanism to the receptor. Deciphering the structural role of histidine 83 for heme binding in hemophore HasA.,Caillet-Saguy C, Turano P, Piccioli M, Lukat-Rodgers GS, Czjzek M, Guigliarelli B, Izadi-Pruneyre N, Rodgers KR, Delepierre M, Lecroisey A J Biol Chem. 2008 Feb 29;283(9):5960-70. Epub 2007 Dec 27. PMID:18162469[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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