Bacterial and archaeal globins — A revised perspective

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 (~1.3Mbp) of the SAR11 clade of alphaproteobacteria and the slightly larger (ca. 1.7Mbp) genomes of Aquificae. The smallest genome with members of all three families is the 2.3Mbp 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.

Exploring three different expression systems for recombinant expression of globins: Escherichia coli, Pichia pastoris and Spodoptera frugiperda

“…The recent and rapid accumulation of genomic information has resulted in a substantial increase in newly recognized globins. Bioinformatic genome surveys revealed that more than 50% of the bacterial, approximately 20% of the archaeal and almost 90% of the eukaryote genomes contain genes encoding globins [1,[5][6][7]. Despite their great variety in function and amino acid sequence, most of them share a similar three-dimensional structure, referred to as the globin fold, characterized by a three-over-three alpha helical folding.…”

Structural flexibility of the heme cavity in the cold‐adapted truncated hemoglobin from the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125

“…A comprehensive nomenclature, including prokaryotic and eukaryotic globins, assigns globins to three distinct families: (a) the myoglobin (Mb)-like family displaying the classical three-on-three (3/3) a-helical sandwich fold, and including flavohemoglobins (FHbs) and single-domain globins; (b) the sensor globin family; and (c) the truncated hemoglobin (TrHb) family that displays the two-on-two (2/2) a-helical sandwich fold [1]. Members of the TrHb family have been found in eubacteria, cyanobacteria, protozoa and plants, but not in animals [2].…”

Globins Scavenge Sulfur Trioxide Anion Radical

“…For example, FMNH ⅐ formed via photoreduction reduces O 2 to ⅐ O 2 Ϫ , and ⅐ O 2 Ϫ can diminish or enhance the apparent O 2 rate constant by acting as a facile STAR reactant or STAR generator (9,11). STAR Toxicity Detoxification in Yeast-Evidence for damage to critical targets and scavenger protection within cells is essential for demonstrating a detoxification function (35,38,40). S. cerevisiae, an organism bearing mitochondria that produce sulfite (41, 42) but lack the sulfite-detoxifying sulfite oxidase (43) and that harbor the STAR-scavenging flavoHb (Yhb1p) .…”