Structural Characterization of a Group II 2/2 Hemoglobin from the Plant Pathogen Agrobacterium Tumefaciens.Pesce, A., Nardini, M., Labarre, M., Richard, C., Wittenberg, J.B., Wittenberg, B.A., Guertin, M., Bolognesi, M.
(2011) Biochim.Biophys.Acta 1814: 810
- PubMed: 21070893
- DOI: 10.1016/j.bbapap.2010.11.001
- PubMed Abstract:
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 ...
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 2.1Å 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. This article is part of a Special Issue entitled: Protein Structure and Function in the Crystalline State.
Department of Physics, University of Genova, I-16146 Genova, Italy.