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Molecular evolution of thyroid peroxidase
1Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041, USA.
Biochimie
|July 14, 1999
Summary
Animal peroxidases, including thyroid peroxidase (TPO), share conserved active sites across species. These findings suggest animal peroxidases evolved independently and likely represent convergent evolution.
Area of Science:
- Biochemistry
- Evolutionary Biology
- Enzymology
Background:
- Thyroid peroxidase (TPO) belongs to the mammalian peroxidase family.
- Homologous protein sequences found in invertebrates suggest a broader family of animal peroxidases.
- Key active site residues are conserved across mammalian and invertebrate peroxidases.
Purpose of the Study:
- To investigate the evolutionary relationship between mammalian and invertebrate peroxidases.
- To determine the conservation of critical amino acid residues in animal peroxidases.
- To re-evaluate the classification of animal peroxidases.
Main Methods:
- Multiple sequence alignment of five mammalian and six invertebrate peroxidases.
- Analysis of conserved amino acid residues essential for peroxidase compound 1 formation.
- Comparison of structural and functional characteristics between animal and non-animal peroxidases.
Main Results:
- Complete conservation of essential residues (distal/proximal histidines, catalytic arginine, hydrogen-bonded asparagine) was observed.
- Thyroid peroxidase-2 (TPO-2), an alternatively spliced form, lacks the essential asparagine.
- Animal peroxidases exhibit significant structural differences from plant/fungal/bacterial peroxidases but share functional similarities.
Conclusions:
- The family of animal peroxidases is broader than previously recognized, encompassing invertebrates.
- Animal peroxidases likely evolved independently from non-animal peroxidases, representing convergent evolution.
- The conserved active site suggests a common functional mechanism despite distinct evolutionary origins.
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