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Chemical Triphosphorylation of Oligonucleotides
Published on: June 2, 2022
Phosphate-tagged substrate recognition by a PrmC-like methyltransferase in apramycin biosynthesis
Qian Zhang1, Yixin Zhang1, Yuting Cui1
1Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Disease, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
International Journal of Biological Macromolecules
|June 15, 2026
Summary
Apramycin biosynthesis uses a unique O-5 phosphorylation tag. The AprI enzyme, a PrmC-like methyltransferase, recognizes this tag to modify the pseudotrisaccharide, enabling site-selective aminoglycoside diversification.
Area of Science:
- Biochemistry
- Molecular Biology
- Natural Product Biosynthesis
Background:
- Apramycin biosynthesis involves O-5 phosphorylation of pseudotrisaccharide intermediates.
- AprI catalyzes 7'-N-methylation of these phosphorylated intermediates.
- AprI's classification within the HemK/PrmC superfamily was unexpected for a small-molecule N-methyltransferase.
Purpose of the Study:
- To elucidate the structural basis of AprI's substrate recognition and catalytic mechanism.
- To understand how AprI, a protein methyltransferase, acts on a small molecule.
- To explore the potential for engineering AprI for biocatalysis.
Main Methods:
- X-ray crystallography of AprI (apo and SAH-bound forms).
- Structure-guided docking and molecular dynamics simulations.
- Mutational analysis of AprI.
Main Results:
- AprI forms a clasp-like homodimer with a composite pocket recognizing the O-5 phosphate tag.
- A dynamic substrate-proximal loop positions the pseudotrisaccharide for methylation.
- AprI functions as a PrmC-like enzyme repurposed for phosphorylated natural products.
Conclusions:
- AprI utilizes a unique mechanism for recognizing phosphorylated natural product intermediates.
- The findings reveal AprI as a PrmC-like methyltransferase adapted for small molecule modification.
- This work opens avenues for engineering biocatalysts for aminoglycoside diversification.
