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Peptidyl-tRNA hydrolase from Sulfolobus solfataricus
Michel Fromant1, Maria-Laura Ferri-Fioni, Pierre Plateau
1Laboratoire de Biochimie, Unité Mixte de Recherche 7654, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Nucleic Acids Research
|June 12, 2003
Summary
Researchers discovered an archaeal enzyme that recycles peptidyl-tRNA (tRNA with an amino acid attached), distinct from bacterial enzymes. This enzyme and its homologs in eukaryotes suggest two types of tRNA recycling pathways exist across life.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Peptidyl-tRNA hydrolase (PTH) is crucial for recycling tRNA in bacteria.
- The specificity and evolutionary origins of PTH enzymes are not fully understood across all domains of life.
Purpose of the Study:
- To characterize a novel enzyme from Sulfolobus solfataricus with peptidyl-tRNA hydrolase activity.
- To investigate the evolutionary conservation and functional significance of archaeal PTH homologs in eukaryotes.
Main Methods:
- Enzyme purification from Sulfolobus solfataricus.
- N-terminal sequencing and gene identification (SS00175).
- Complementation assays in E. coli lacking PTH activity.
- In vitro enzymatic assays using diacetyl-lysyl-tRNA(Lys) and formyl-methionyl-tRNA(fMet).
- Gene disruption and growth analysis in Saccharomyces cerevisiae.
Main Results:
- A S. solfataricus enzyme capable of liberating functional tRNA(Lys) was purified.
- The archaeal enzyme accepts E. coli formyl-methionyl-tRNA(fMet) and complements E. coli lacking PTH, indicating functional similarity but distinct substrate specificity compared to bacterial PTH.
- Homologs of the archaeal gene are found across archaea and eukaryotes, suggesting a conserved, potentially ancient, tRNA recycling pathway.
- Saccharomyces cerevisiae possesses both bacterial-like (YHR189w) and archaeal-like (YBL057c) PTH genes, each capable of rescuing E. coli lacking PTH.
- Disruption of YHR189w in yeast suggests its involvement in mitochondrial function.
Conclusions:
- A distinct archaeal peptidyl-tRNA hydrolase pathway exists, conserved in eukaryotes.
- Eukaryotes may possess two types of PTH activities: bacterial and archaeal.
- The bacterial-like PTH in yeast (YHR189w) plays a role in mitochondrial function.