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Orphan SelD proteins and selenium-dependent molybdenum hydroxylases.
Daniel H Haft1, William T Self
1Department of Bioinformatics, J, Craig Venter Institute, Rockville, MD 20850, USA. haft@jcvi.org
Biology Direct
|February 22, 2008
Summary
Researchers found the selD gene in two species lacking known selenium pathways. This suggests new selenium-dependent molybdenum hydroxylases may exist, identifiable by surrounding genes.
Area of Science:
- Microbiology
- Biochemistry
- Genomics
Background:
- Prokaryotes utilize selenium in selenouridine-modified tRNAs, selenocysteine-translated proteins, and selenium-dependent molybdenum hydroxylases (SDMH).
- The selenophosphate synthetase gene (selD) is crucial for tRNA and protein selenium incorporation.
- SDMH represent a distinct class of selenium-utilizing enzymes.
Purpose of the Study:
- To investigate the distribution and potential novel functions of the selD gene in prokaryotic genomes.
- To identify potential new selenium-dependent molybdenum hydroxylases beyond known pathways.
Main Methods:
- Analysis of over 500 complete prokaryotic genomes.
- Comparative genomics to identify conserved gene clusters around the selD gene.
- Partial Phylogenetic Profiling to detect co-evolutionary patterns.
Main Results:
- The selD gene was identified in two species, Enterococcus faecalis and Haloarcula marismortui, which lack known selenocysteine and selenouridine systems.
- Candidate genes for molybdenum hydroxylase subunits and accessory proteins were found adjacent to these 'orphan' selD genes.
- These surrounding genes showed conserved patterns and co-evolution with selD.
Conclusions:
- The presence of orphan selD genes in E. faecalis and H. marismortui suggests previously unrecognized selenium utilization pathways.
- The identified accessory proteins and orphan selD genes can serve as markers for discovering novel SDMH.
- This finding expands our understanding of selenium's role in prokaryotic biochemistry.
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