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Single-strand-preferring RNases degrade double-stranded RNAs by destabilizing its secondary structure
G Yakovlev1, G P Moiseyev, S Sorrentino
1Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia. yakovlev@imb.imb.ac.ru
Journal of Biomolecular Structure & Dynamics
|December 17, 1997
Summary
Human and bovine seminal ribonucleases efficiently degrade double-stranded RNA (dsRNA) by destabilizing its structure, unlike RNase A. This enhanced activity is linked to their higher positive charge, aiding dsRNA depolymerization.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Mammalian single-stranded-preferring ribonucleases (RNases) play roles in RNA metabolism.
- The influence of non-catalytic amino acid residues on RNase activity, particularly towards double-stranded RNA (dsRNA), is not fully understood.
Purpose of the Study:
- To elucidate the mechanism of dsRNA degradation by mammalian single-stranded-preferring RNases.
- To investigate the role of positively charged non-catalytic amino acid residues in RNase activity on dsRNA.
Main Methods:
- Studied kinetic parameters of polyribonucleotide depolymerization using human seminal RNase, bovine seminal RNase, and ox pancreas RNase A.
- Assayed activity on single-stranded (poly(U), poly(C)) and double-stranded (poly(U).poly(A), poly(C).poly(I)) substrates.
- Evaluated enzyme activity under physiological salt conditions (0.16 M).
Main Results:
- Human and bovine seminal RNases showed similar activity on poly(U).poly(A) and poly(U) under physiological salt conditions.
- RNase A exhibited a ten times higher ratio of activity on poly(U) versus poly(U).poly(A) compared to seminal RNases.
- Seminal RNases demonstrated higher destabilizing action on poly(U).poly(A) duplexes, attributed to their greater positive charge and affinity for poly(A).
Conclusions:
- Human and bovine seminal RNases are more efficient than RNase A in depolymerizing poly(U).poly(A) at physiological ionic strength.
- The enhanced activity of seminal RNases on dsRNA is linked to their higher positive charge, facilitating destabilization and binding to the poly(A) strand.