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5'-terminal glycosylation of protein-coding transcripts: An epitranscriptomic modification that prolongs mRNA
Tithi Banerjee1, Daniel J Luciano1, Joel G Belasco1
1Department of Microbiology, New York University School of Medicine, New York, NY 10016.
Summary
Researchers discovered a new type of RNA modification in E. coli: a 5'-terminal glucose cap on messenger RNAs (mRNAs). This capping protects mRNA from degradation, potentially regulating bacterial protein synthesis.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Glycosylation is a common post-translational modification affecting proteins, lipids, and polysaccharides.
- RNA modifications, including capping, are crucial for RNA stability and function.
- Existing RNA caps are typically removed enzymatically, regulating RNA lifespan.
Purpose of the Study:
- To investigate novel forms of glycosylation beyond known macromolecules.
- To identify and characterize new RNA capping mechanisms in bacteria.
- To understand the functional implications of these novel RNA caps.
Main Methods:
- Analysis of RNA modifications in Escherichia coli.
- Identification of 5'-terminal modifications on U-initiated mRNAs.
- Assessment of the stability of capped versus uncapped mRNAs.
- Investigating the enzymatic removal of the identified caps.
Main Results:
- Discovered 5'-terminal glucose caps on U-initiated mRNAs in E. coli, present on 30-40% of transcripts.
- Observed no N-acetylglucosamine caps.
- Demonstrated that glucose caps resist enzymatic removal, prolonging mRNA cellular lifetime.
- Showed that glucose caps impede 5'-end-dependent mRNA degradation.
Conclusions:
- Protein-coding transcripts can be glycosylated at the 5' end with glucose.
- This noncanonical capping is prevalent in E. coli and enhances mRNA stability.
- Glucose capping represents a significant epitranscriptomic modification with potential regulatory roles in bacterial gene expression.
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