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DbpA: a DEAD box protein specifically activated by 23s rRNA
F V Fuller-Pace1, S M Nicol, A D Reid
1Department of Biochemistry, University of Dundee, UK.
The EMBO Journal
|September 1, 1993
Summary
Escherichia coli DbpA protein uses an unusual GUG start codon for translation. Its RNA-dependent ATPase activity specifically requires 23S rRNA, unlike other DEAD box proteins.
Area of Science:
- Molecular Biology
- Biochemistry
Background:
- Escherichia coli DbpA is a DEAD box protein involved in RNA metabolism.
- DEAD box proteins are characterized by the conserved Asp-Glu-Ala-Asp motif and function as ATPases and RNA helicases.
Purpose of the Study:
- To investigate the expression and biochemical activity of the Escherichia coli DbpA protein.
- To identify the specific RNA requirement for DbpA's ATPase activity.
Main Methods:
- Investigated DbpA expression using its endogenous promoter.
- Analyzed translation initiation by mutating the GUG start codon.
- Purified DbpA via inducible overexpression.
- Assayed RNA-dependent ATP hydrolysis activity.
Main Results:
- DbpA translation initiates at an upstream GUG codon, not the previously identified AUG.
- Mutation of the GUG codon significantly reduces DbpA expression.
- Purified DbpA exhibits RNA-dependent ATP hydrolysis.
- This ATPase activity is absolutely dependent on 23S rRNA, despite DbpA binding other nucleic acids.
Conclusions:
- DbpA utilizes an atypical translation initiation mechanism involving a GUG codon.
- DbpA possesses a unique RNA-dependent ATPase activity specifically requiring 23S rRNA.
- This finding highlights a specialized role for DbpA in bacterial RNA processing or function.