The PR-10 Protein Pru p 1 is an Endonuclease that Preferentially Cleaves Single-Stranded RNA

Area of Science:

• Plant biochemistry
• Molecular biology
• Enzymology

Background:

• Pathogenesis-related class 10 (PR-10) proteins are vital for plant defense mechanisms.
• Their specific functions as ribonucleases and substrate interactions are not fully understood.

Purpose of the Study:

• To investigate the enzymatic activity and substrate specificity of Pru u2005p u20091, a PR-10 protein from peach.
• To elucidate the mechanism of RNA cleavage by PR-10 proteins.

Main Methods:

• Enzymatic assays to determine RNA cleavage activity.
• Kinetic analysis to identify initial cleavage products.
• Nuclear Magnetic Resonance (NMR) binding site mapping.
• Structure-based mechanistic modeling.

Main Results:

• Pru u2005p u20091 exhibits endonucleolytic activity, cleaving RNA into short oligonucleotides.
• Initial RNA fragments can re-bind to the enzyme, facilitating further degradation.
• NMR mapping identified the internal cavity of Pru u2005p u20091 as an RNA binding site.
• Zeatin, a nucleoside analog, was found to inhibit Pru u2005p u20091 ribonuclease activity.

Conclusions:

• A detailed mechanistic model for Pru u2005p u20091's ribonuclease activity was proposed.
• The study clarifies the role of the PR-10 protein's internal cavity in substrate binding and degradation.
• Findings provide insights into plant defense strategies involving RNA degradation.