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Structural determinants of ligand migration in Mycobacterium tuberculosis truncated hemoglobin O
Author(s) -
Boechi Leonardo,
Martí Marcelo A.,
Milani Mario,
Bolognesi Martino,
Luque F. Javier,
Estrin Darío A.
Publication year - 2008
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.22072
Subject(s) - ligand (biochemistry) , mycobacterium tuberculosis , tuberculosis , hemoglobin , chemistry , kinetics , mutant , docking (animal) , biology , gene , computational biology , crystallography , genetics , biochemistry , receptor , physics , medicine , nursing , pathology , quantum mechanics
Mycobacterium tuberculosis is the causative agent of human tuberculosis, one of the most prevalent infectious diseases in the world. Its genome hosts the glbN and glbO genes coding for two proteins, truncated hemoglobin N (trHbN) and truncated hemoglobin O (trHbO), that belong to different groups (I and II, respectively) of the recently discovered trHb family of hemeproteins. The different expression pattern and kinetics rates constants for ligand association and NO oxidation rate suggest different functions for these proteins. Previous experimental and theoretical studies showed that, in trHbs, ligand migration along the internal tunnel cavity system is a key issue in determining the ligand‐binding characteristics. The X‐ray structure of trHbO has been solved and shows several internal cavities and secondary‐docking sites. In this work, we present an extensive investigation of the tunnel/cavity system ofM. tuberculosis trHbO by means of computer‐simulation techniques. We have computed the free‐energy profiles for ligand migration along three found tunnels in the oxy and deoxy w.t. and mutant trHbO proteins. Our results show that multiple‐ligand migration paths are possible and that several conserved residues such as TrpG8 play a key role in the ligand‐migration regulation. Proteins 2008. © 2008 Wiley‐Liss, Inc.