3A9M

Crystal structure of a hemoglobin component V from Propsilocerus akamusi (pH9.0 coordinates)

Summary for 3A9M

• Entry DOI: 10.2210/pdb3a9m/pdb
• Related: 2ZWJ 3A5A 3A5B 3A5G
• Descriptor: Hemoglobin V, PROTOPORPHYRIN IX CONTAINING FE, CARBON MONOXIDE, ... (4 entities in total)
• Functional Keywords: hemoglobin, insect, diptera, propsilocerus akamusi, midge larva, heme, oxygen transport, transport
• Biological source: Tokunagayusurika akamusi
• Total number of polymer chains: 1
• Total formula weight: 17863.84

Authors

Kuwada, T.,Hasegawa, T.,Takagi, T.,Shishikura, F. (deposition date: 2009-10-30, release date: 2010-03-23, Last modification date: 2023-11-01)

Primary citation

Kuwada, T.,Hasegawa, T.,Takagi, T.,Sato, I.,Shishikura, F.
pH-dependent structural changes in haemoglobin component V from the midge larva Propsilocerus akamusi (Orthocladiinae, Diptera)
Acta Crystallogr.,Sect.D, 66:258-267, 2010

PubMed Abstract: Haemoglobin component V (Hb V) from the midge larva Propsilocerus akamusi exhibits oxygen affinity despite the replacement of HisE7 and a pH-dependence of its functional properties. In order to understand the contribution of the distal residue to the ligand-binding properties and the pH-dependent structural changes in this insect Hb, the crystal structure of Hb V was determined under five different pH conditions. Structural comparisons of these Hb structures indicated that at neutral pH ArgE10 contributes to the stabilization of the haem-bound ligand molecule as a functional substitute for the nonpolar E7 residue. However, ArgE10 does not contribute to stabilization at acidic and alkaline pH because of the swinging movement of the Arg side chain under these conditions. This pH-dependent behaviour of Arg results in significant differences in the hydrogen-bond network on the distal side of the haem in the Hb V structures at different pH values. Furthermore, the change in pH results in a partial movement of the F helix, considering that coupled movements of ArgE10 and the F helix determine the haem location at each pH. These results suggested that Hb V retains its functional properties by adapting to the structural changes caused by amino-acid replacements.

PubMed: 20179337
DOI: 10.1107/S0907444909055760

Experimental method

X-RAY DIFFRACTION (1.8 Å)