Truncated hemoglobins (trHbs) build a sub-class of the globin family, found in eubacteria, cyanobacteria, unicellular eukaryotes, and in higher plants; among these, selected human pathogens are found. The trHb fold is based on a 2/2 alpha-helical sandwich, consisting of a simplified and reduced-size version of the classical 3/3 alpha-helical sandwich of vertebrate and invertebrate globins. Phylogenetic analysis indicates that trHbs further branch into three groups: group I (or trHbN), group II (or trHbO), and group III (or trHbP), each group being characterized by specific structural features. Among these, a protein matrix tunnel, or a cavity system implicated in diatomic ligand diffusion through the protein matrix, is typical of group I and group II, respectively. In general, a highly intertwined network of hydrogen bonds stabilizes the heme bound ligand, despite variability of the heme distal residues in the different trHb groups. Notably, some organisms display genes from more than one trHb group, suggesting that trHbN, trHbO, and trHbP may support different functions in vivo, such as detoxification of reactive nitrogen and oxygen species, respiration, oxygen storage/sensoring, thus aiding survival of an invading microorganism. Here, structural features and proposed functions of trHbs from human pathogens are reviewed.

Truncated (2/2) hemoglobin : Unconventional structures and functional roles in vivo and in human pathogenesis / M. Nardini, A. Pesce, M. Bolognesi. - In: MOLECULAR ASPECTS OF MEDICINE. - ISSN 0098-2997. - 84:(2022 Apr), pp. 101049.1-101049.8. [10.1016/j.mam.2021.101049]

Truncated (2/2) hemoglobin : Unconventional structures and functional roles in vivo and in human pathogenesis

M. Nardini
Primo
Writing – Original Draft Preparation
;
M. Bolognesi
Ultimo
Writing – Review & Editing
2022

Abstract

Truncated hemoglobins (trHbs) build a sub-class of the globin family, found in eubacteria, cyanobacteria, unicellular eukaryotes, and in higher plants; among these, selected human pathogens are found. The trHb fold is based on a 2/2 alpha-helical sandwich, consisting of a simplified and reduced-size version of the classical 3/3 alpha-helical sandwich of vertebrate and invertebrate globins. Phylogenetic analysis indicates that trHbs further branch into three groups: group I (or trHbN), group II (or trHbO), and group III (or trHbP), each group being characterized by specific structural features. Among these, a protein matrix tunnel, or a cavity system implicated in diatomic ligand diffusion through the protein matrix, is typical of group I and group II, respectively. In general, a highly intertwined network of hydrogen bonds stabilizes the heme bound ligand, despite variability of the heme distal residues in the different trHb groups. Notably, some organisms display genes from more than one trHb group, suggesting that trHbN, trHbO, and trHbP may support different functions in vivo, such as detoxification of reactive nitrogen and oxygen species, respiration, oxygen storage/sensoring, thus aiding survival of an invading microorganism. Here, structural features and proposed functions of trHbs from human pathogens are reviewed.
Globin fold; Heme; NO-dioxygenase reaction; RNS detoxification; ROS detoxification; Truncated hemoglobin; Humans; Ligands; Phylogeny; Proteins; Heme; Truncated Hemoglobins
Settore BIO/10 - Biochimica
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
12-nov-2021
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/944396
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