Tinkering with coordination in globins

LUCIA CHISARI, IGNACIO BORON, LUCIANA CAPECE, MARCELO MARTI, DARIO ESTRIN AND ALEJANDRO NADRA

Congreso; 4to. Congreso Argentino de Bioinformática y Biología Computacional (4CAB2C) y 4ta. Conferencia Internacional de la Sociedad Iberoamericana de Bioinformática (SolBio); 2013

Introduction Myoglobin (Mb) is a pentacoordinated hemeprotein that allows oxygen transport inside the muscle. Recently, another member of this family has been found: neuroglobin (Ngb). Ngb is present in vertebrates and other organisms´ nervous system. It binds small gaseous ligands in the heme group´s sixth coordination position. In absence of these ligands, the heme group binds to an endogenous histidine. It has been suggested that this bond and the equilibrium between the hexacoordinated and the pentacoordinated state regulate ligand affinity. Recent studies  have revealed that neuroglobin´s changes in coordination correlate to changes in the C-CD-D region. By swapping neuroglobin´s and myoglobin´s CD loops (both in silico and in vitro), Nadra et al. found that each chimeric protein shifted its coordination state according to its CD region, as shown for the partially hexacoordinated Mb or the subtly pentacoordinated Ngb.