2xyk

Publication Abstract from PubMed

Within the 2/2 hemoglobin sub-family, no group II 2/2Hbs from proteobacteria have been so far studied. Here we present the first structural characterization of a group II 2/2Hb from the soil and phytopathogenic bacterium Agrobacterium tumefaciens (At-2/2HbO). The crystal structure of ferric At-2/2HbO (reported at 2.1A resolution) shows the location of specific/unique heme distal site residues (e.g., His(42)CD1, a residue distinctive of proteobacteria group II 2/2Hbs) that surround a heme-liganded water molecule. A highly intertwined hydrogen-bonded network, involving residues Tyr(26)B10, His(42)CD1, Ser(49)E7, Trp(93)G8, and three distal site water molecules, stabilizes the heme-bound ligand. Such a structural organization suggests a path for diatomic ligand diffusion to/from the heme. Neither a similar distal site structuring effect nor the presence of distal site water molecules has been so far observed in group I and group III 2/2Hbs, thus adding new distinctive information to the complex picture of currently available 2/2Hb structural and functional data.

Structural characterization of a group II 2/2 hemoglobin from the plant pathogen Agrobacterium tumefaciens.,Pesce A, Nardini M, Labarre M, Richard C, Wittenberg JB, Wittenberg BA, Guertin M, Bolognesi M Biochim Biophys Acta. 2010 Nov 9. PMID:21070893^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.