Ribonucleases protect RNA from acid precipitation

Area of Science:

• Biochemistry
• Molecular Biology

Background:

• Ribonucleases (RNases) are crucial enzymes in RNA metabolism.
• Their activity is typically measured by quantifying acid-soluble degradation products.
• RNase activity assays are fundamental for enzyme purification and functional studies.

Purpose of the Study:

• To investigate a previously unrecognized protective effect of RNases on their substrates.
• To characterize the factors influencing this protective phenomenon.
• To assess the implications of this effect on standard RNase activity assays.

Main Methods:

• Assessing substrate protection from acid precipitation by four different RNases.
• Evaluating the influence of nucleotides (UMP, CMP, IMP) and divalent ions (Zn++, Co++, Cu++) on protection.
• Investigating the role of substrate hybridization with complementary ribohomopolymers.
• Localizing the protective domain of bovine pancreatic ribonuclease using S-protein.

Main Results:

• Four RNases demonstrated substrate protection from acid precipitation via physicochemical modification.
• Protection varied with substrate type and was modulated by nucleotides and divalent ions.
• Hybridization with complementary ribohomopolymers abolished protection.
• Bovine pancreatic ribonuclease S-protein, lacking nucleolytic activity, mediated protection.
• RNase S-protein enhanced the catalytic activity of Bacillus cereus RNase and potentially other RNases like onconase.

Conclusions:

• RNase-mediated substrate protection can lead to inaccurate measurements in standard activity assays.
• This property necessitates careful consideration during RNase purification and functional analysis.
• RNase S-protein exhibits a dual role, offering substrate protection and enhancing catalytic activity, with potential therapeutic implications.