Structural and dynamics characterization of the hexacoordinated globin from Spisula solidissima

Journal of Inorganic Biochemistry(2023)

引用 0|浏览14
暂无评分
摘要
High energy consumption in the nervous system requires a continuous supply of O2. This role is assisted by proteins from the globin super-family in the nerve cells of invertebrates, where ‘nerve hemoglobins’ (nHbs) are mainly present at mM concentrations and exhibit oxygen affinities comparable to those of vertebrate myoglobins. To gain insight into the structural bases of this function, we report the crystal structure of nHb from the Atlantic surf clam Spisula solidissima (SsHb), previously suggested to display a bis-histidyl hexacoordinated heme in the deoxy state, high O2 affinity, and ligand binding cooperativity when assayed in situ. The crystallized protein forms a dimer through packing of a 4-helix bundle involving helices E and F of each subunit. The SsHb ‘classic’ globin fold displays bis-histidyl (His71(E7) and His103(F8)) hexacoordination of the heme-Fe atom, with structural and dynamics variations found in the inter-helix hinge regions. Molecular Dynamics simulations of both monomeric and dimeric species in the bis-histidyl hexacoordinated, deoxy penta-coordinated, and O2-bound hexacoordinated states reveal distinct structural rearrangements at the interface between subunits in the dimer; these would affect the magnitude of the conformational fluctuations observed between monomer and dimer, and the topology of cavities within the protein matrix and at the interface. These results point to a distal site opening mechanism allowing access of the exogenous ligand to the heme and cast hypotheses on the dimer interface structural and dynamic properties that may support ligand binding cooperativity in dimeric SsHb.
更多
查看译文
关键词
hexacoordinated globin
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要