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Structural characterization of an Ascaris myoglobin
M L Blaxter1, J R Vanfleteren, J Xia
1Department of Biology, Imperial College of Science, London, United Kingdom.
The Journal of Biological Chemistry
|December 2, 1994
Summary
This study purified and sequenced Ascaris suum body wall globin, revealing a cytosolic myoglobin-like protein. Evolutionary analysis suggests nematode globins diverged significantly over 500 million years ago.
Area of Science:
- Parasitic Nematode Biology
- Molecular Evolution
- Protein Biochemistry
Background:
- Ascaris suum, a parasitic nematode, possesses multiple globin types.
- Understanding globin function and evolution in nematodes is crucial for parasitic organism research.
Purpose of the Study:
- To characterize the body wall globin of Ascaris suum.
- To investigate the evolutionary relationships of nematode globins.
Main Methods:
- Purification of globin from Ascaris suum.
- Peptide sequencing and cDNA isolation via polymerase chain reaction.
- Bioinformatic and evolutionary analyses.
Main Results:
- Isolated a 154-amino acid cytosolic myoglobin-like polypeptide lacking a signal sequence.
- The native protein exists as a dimer with unusual amino acid substitutions.
- Body wall globin exhibits 10-fold lower oxygen affinity compared to pseudocoelomic hemoglobin.
- Evolutionary divergence of nematode globins estimated at ~500 million years ago.
- Ascaris suum myoglobin gene lacks introns, unlike other nematode globin genes.
Conclusions:
- Ascaris suum body wall globin is a distinct cytosolic myoglobin-like molecule.
- Evolutionary history indicates early divergence of nematode globin types.
- Intron loss may have played a significant role in nematode globin gene evolution.