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Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules

Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O (2) and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO...

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Autores principales: Boron, Ignacio, Bustamante, Juan Pablo, Davidge, Kelly S, Singh, Sandip, Bowman, Lesley AH, Tinajero-Trejo, Mariana, Carballal, Sebastián, Radi, Rafael, Poole, Robert K, Dikshit, Kanak, Estrin, Dario A, Marti, Marcelo A, Boechi, Leonardo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: F1000Research 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4591903/
https://www.ncbi.nlm.nih.gov/pubmed/26478812
http://dx.doi.org/10.12688/f1000research.5921.2
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author Boron, Ignacio
Bustamante, Juan Pablo
Davidge, Kelly S
Singh, Sandip
Bowman, Lesley AH
Tinajero-Trejo, Mariana
Carballal, Sebastián
Radi, Rafael
Poole, Robert K
Dikshit, Kanak
Estrin, Dario A
Marti, Marcelo A
Boechi, Leonardo
author_facet Boron, Ignacio
Bustamante, Juan Pablo
Davidge, Kelly S
Singh, Sandip
Bowman, Lesley AH
Tinajero-Trejo, Mariana
Carballal, Sebastián
Radi, Rafael
Poole, Robert K
Dikshit, Kanak
Estrin, Dario A
Marti, Marcelo A
Boechi, Leonardo
author_sort Boron, Ignacio
collection PubMed
description Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O (2) and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify (•)NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, (•)NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations affect both the tunnels accessibility as well as the affinity of distal site water molecules, thus modifying the ligand access to the iron. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.
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spelling pubmed-45919032015-10-15 Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules Boron, Ignacio Bustamante, Juan Pablo Davidge, Kelly S Singh, Sandip Bowman, Lesley AH Tinajero-Trejo, Mariana Carballal, Sebastián Radi, Rafael Poole, Robert K Dikshit, Kanak Estrin, Dario A Marti, Marcelo A Boechi, Leonardo F1000Res Research Article Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O (2) and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify (•)NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, (•)NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations affect both the tunnels accessibility as well as the affinity of distal site water molecules, thus modifying the ligand access to the iron. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site. F1000Research 2015-07-22 /pmc/articles/PMC4591903/ /pubmed/26478812 http://dx.doi.org/10.12688/f1000research.5921.2 Text en Copyright: © 2015 Boron I et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Boron, Ignacio
Bustamante, Juan Pablo
Davidge, Kelly S
Singh, Sandip
Bowman, Lesley AH
Tinajero-Trejo, Mariana
Carballal, Sebastián
Radi, Rafael
Poole, Robert K
Dikshit, Kanak
Estrin, Dario A
Marti, Marcelo A
Boechi, Leonardo
Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title_full Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title_fullStr Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title_full_unstemmed Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title_short Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
title_sort ligand uptake in mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4591903/
https://www.ncbi.nlm.nih.gov/pubmed/26478812
http://dx.doi.org/10.12688/f1000research.5921.2
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