Premium
Reversible hexa‐ to penta‐coordination of the heme Fe atom modulates ligand binding properties of neuroglobin and cytoglobin
Author(s) -
Pesce Alessandra,
De Sanctis Daniele,
Nardini Marco,
Dewilde Sylvia,
Moens Luc,
Hankeln Thomas,
Burmester Thorsten,
Ascenzi Paolo,
Bolognesi Martino
Publication year - 2004
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216540500078830
Subject(s) - neuroglobin , heme , globin , ligand (biochemistry) , myoglobin , chemistry , hexa , hemeprotein , biochemistry , biophysics , hemoglobin , biology , enzyme , receptor
Neuroglobin (Ngb) and cytoglobin (Cygb) are two recently discovered intracellular members of the vertebrate hemoglobin (Hb) family. Ngb, predominantly expressed in nerve cells, is of ancient evolutionary origin and is homologous to nerve‐globins of invertebrates. Cygb, present in many different tissues, shares common ancestry with myoglobin (Mb) and can be traced to early vertebrate evolution. Ngb is held to facilitate O2 diffusion to the mitochondria and to protect neuronal cells from hypoxic‐ischemic insults, may be an oxidative stress‐responsive sensor protein for signal transduction, and may carry out enzymatic activities, such as NO/O2 scavenging. Cygb is linked to collagen synthesis, may provide O2 for enzymatic reactions, and may be involved in a ROS (NO)‐signaling pathway(s). Ngb and Cgb display the classical three‐over‐three α‐helical fold of Hb and Mb, and are endowed with a hexa‐coordinate heme‐Fe atom, in their ferrous and ferric forms, having the heme distal HisE7 residue as the endogenous ligand. Reversible hexa‐ to penta‐coordination of the heme Fe atom modulates ligand binding properties of Ngb and Cygb. Moreover, Ngb and Cygb display a tunnel/cavity system within the protein matrix held to facilitate ligand channeling to/from the heme, multiple ligand copies storage, multi‐ligand reactions, and conformational transitions supporting ligand binding.IUBMB Life, 56: 657‐664, 2004