Bacterial and archaeal globins — A revised perspective |
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Authors: | Serge N. Vinogradov Mariana Tinajero-Trejo Robert K. Poole David Hoogewijs |
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Affiliation: | 1. Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA;2. Institute of Biology and Biotechnology, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom;3. Institute of Physiology and Zürich Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland |
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Abstract: | A bioinformatics survey of putative globins in over 2200 bacterial and some 140 archaeal genomes revealed that over half the bacterial and approximately one fifth of archaeal genomes contain genes encoding globins that were classified into three families: the M (myoglobin-like), and S (sensor) families all exhibiting the canonical 3/3 myoglobin fold, and the T family (truncated myoglobin fold). Although the M family comprises 2 subfamilies, flavohemoglobins (FHbs) and single domain globins (SDgbs), the S family encompasses chimeric globin-coupled sensors (GCSs), single domain Pgbs (protoglobins) and SSDgbs (sensor single domain globins). The T family comprises three classes TrHb1s, TrHb2s and TrHb3s, characterized by the abbreviated 2/2 myoglobin fold. The Archaea contain only Pgbs, GCSs and TrHb1s. The smallest globin-bearing genomes are the streamlined genomes (~ 1.3 Mbp) of the SAR11 clade of alphaproteobacteria and the slightly larger (ca. 1.7 Mbp) genomes of Aquificae. The smallest genome with members of all three families is the 2.3 Mbp genome of the extremophile Methylacidiphilum infernorum (Verrumicrobia). Of the 147 possible combinations of the eight globin subfamilies, only 83 are observed. Although binary combinations are infrequent and ternary combinations are rare, the FHb + TrHb2 combination is the most commonly observed. Of the possible functions of bacterial globins we discuss the two principal ones — nitric oxide detoxification via the NO dioxygenase or denitrosylase activities and the sensing of oxygen concentration in the environmental niche. In only few cases has a physiological role been demonstrated in vivo. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. |
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Keywords: | Adgb, androglobin Cygb, cytoglobin FHb, flavohaemoglobin GbE, globin E GbX, globin X GbY, globin Y GCS, globin-coupled sensor Hb, haemoglobin HGT, horizontal gene transfer LECA, Last Universal Eukaryote Common Ancestor Mb, myoglobin Ngb, neuroglobin Pgb, protoglobin SDgb, single domain 3/3 globin related to the N-terminal of FHbs SSDgb, sensor single domain 3/3 globin related to the N-terminal of GCSs. |
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