A novel cross-linked RNase A dimer with enhanced enzymatic properties

Area of Science:

• Biochemistry
• Enzymology
• Protein Chemistry

Background:

• Ribonuclease A (RNase A) is a crucial enzyme for RNA degradation.
• Understanding RNase A structure-function relationships is key to developing novel biocatalysts.
• Existing methods for cross-linking RNase A have limitations.

Purpose of the Study:

• To synthesize and characterize a novel cross-linked ribonuclease A (RNase A) dimer.
• To investigate the structural and functional properties of the newly formed dimer.
• To assess the enzymatic activity and inhibitor resistance of the RNase A dimer.

Main Methods:

• Lyophilized RNase A was incubated under vacuum at 85°C to form an amide cross-link between Lys(66) and Glu(9).
• X-ray crystallography was used to examine the dimer's structure and conformation.
• Enzymatic activity assays were performed using double-stranded RNA (dsRNA) and single-stranded RNA (ssRNA) substrates.
• Inhibition assays were conducted using the cellular ribonuclease inhibitor protein (cRI).

Main Results:

• A novel RNase A dimer was successfully prepared via an in vacuo amide cross-linking procedure.
• The cross-linking process did not induce significant conformational changes but resulted in an acid-labile, strained cross-link.
• The novel dimer exhibits a twofold increase in enzymatic activity compared to monomeric RNase A for both dsRNA and ssRNA.
• The cross-linked RNase A dimer demonstrated resistance to inhibition by cRI.

Conclusions:

• The in vacuo preparation yields a novel, conformationally strained RNase A dimer with significantly enhanced catalytic efficiency.
• This cross-linked dimer represents a new structural form of RNase A with potential applications in biotechnology.
• The dimer's resistance to cRI suggests potential advantages in cellular or therapeutic contexts.