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Ancestral hemoglobins in Archaea.
Tracey Allen K Freitas1, Shaobin Hou, Elhadji M Dioum
1Department of Microbiology, Snyder Hall 207, 2538 The Mall, University of Hawaii, Honolulu, HI 96822, USA.
Summary
Researchers discovered two protoglobins (Pgbs) in Archaea, ApPgb and MaPgb, which bind oxygen and other molecules. These findings suggest archaeal globins may be ancient hemoglobin ancestors.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Hemoglobins are widespread in Eukarya and Bacteria but have not been identified in Archaea.
- Phylogenetic analysis suggests microbial globin-coupled sensors evolved from a protoglobin (Pgb) progenitor.
Purpose of the Study:
- To report the discovery and characterization of protoglobins (Pgbs) in Archaea.
- To investigate the potential ancestral role of these archaeal globins in hemoglobin evolution.
Main Methods:
- Phylogenetic analysis of microbial globin-coupled heme-based sensors.
- Biochemical characterization of two archaeal protoglobins (ApPgb and MaPgb).
Main Results:
- Discovery and characterization of ApPgb from Aeropyrum pernix and MaPgb from Methanosarcina acetivorans.
- Both ApPgb and MaPgb were found to bind molecular oxygen, nitric oxide, and carbon monoxide.
- Heme moiety in both Pgbs is coordinated via F8 histidine (histidine 120).
Conclusions:
- The identified archaeal globins (ApPgb and MaPgb) represent the first discovery of Pgbs in Archaea.
- These findings support the hypothesis that archaeal globins are the ancestors of contemporary hemoglobins.
- The study expands the known phylogenetic distribution of globins and provides insights into their evolutionary origins.