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Identification of [2Fe-2S] clusters in microbial ferrochelatases
Tamara A Dailey1, Harry A Dailey
1Department of Microbiology, Center for Metalloenzyme Studies, Biomedical and Health Sciences Institute, University of Georgia, Athens, Georgia 30602-7229, USA.
Journal of Bacteriology
|April 12, 2002
Summary
Microbial ferrochelatases from Caulobacter crescentus and Mycobacterium tuberculosis possess novel [2Fe-2S] clusters. These findings reveal a new class of iron-sulfur proteins in bacteria, expanding our understanding of heme biosynthesis.
Area of Science:
- Biochemistry
- Microbiology
- Structural Biology
Background:
- Ferrochelatase is the terminal enzyme in heme biosynthesis, catalyzing iron insertion into protoporphyrin IX.
- Previously, [2Fe-2S] clusters were known only in animal ferrochelatases, not in prokaryotic or plant homologs.
Purpose of the Study:
- To investigate the presence and characteristics of [2Fe-2S] clusters in prokaryotic ferrochelatases.
- To determine if microbial ferrochelatases represent a new class of iron-sulfur proteins.
Main Methods:
- Spectroscopic analysis to detect and characterize [2Fe-2S] clusters.
- Biochemical and structural analysis of ferrochelatases from Caulobacter crescentus and Mycobacterium tuberculosis.
Main Results:
- Ferrochelatases from C. crescentus and M. tuberculosis were found to possess [2Fe-2S] clusters.
- These microbial clusters exhibit unique cysteine ligation and ligand spacing, distinct from known proteins.
- C. crescentus ferrochelatase is homodimeric and membrane-associated; M. tuberculosis ferrochelatase is monomeric and soluble.
Conclusions:
- Microbial ferrochelatases constitute a novel group of [2Fe-2S] cluster-containing proteins.
- The unique cluster structure suggests distinct evolutionary pathways and functional adaptations in prokaryotes.