Conversion of trypsin into a Na(+)-activated enzyme

Area of Science:

• Biochemistry
• Enzymology
• Protein Engineering

Background:

• Serine proteases in the chymotrypsin family exhibit distinct amino acid properties at residue 225, influencing sodium ion (Na(+)) activation.
• Tyrosine (Tyr) at position 225 confers Na(+) activation, while Proline (Pro) at this position results in no Na(+) binding or activation.
• Previous research showed Y225P mutation abolishes Na(+) activation, but P225Y mutation alone is insufficient for Na(+) activation.

Purpose of the Study:

• To engineer a Na(+)-activated enzyme from a non-activated serine protease.
• To investigate the structural modifications required for introducing Na(+) binding and activation.
• To establish a proof of principle for designing allosterically regulated proteases.

Main Methods:

• Engineering of Streptomyces griseus trypsin (Pro-225) into a Na(+)-activated enzyme.
• Substitution of residues in the 170, 186, and 220 loops with those from coagulation factor Xa.
• Characterization of the engineered enzyme's Na(+) binding and activation properties.

Main Results:

• Successfully engineered a Pro-225 serine protease into a Na(+)-activated enzyme.
• Demonstrated that specific loop residue substitutions are key to introducing Na(+) activation.
• The engineered enzyme exhibits Na(+) binding and activation, unlike the wild-type.

Conclusions:

• This study presents the first engineered Na(+)-activated serine protease.
• The findings provide a foundational principle for designing proteases with tunable allosteric regulation by monovalent cations.
• This work opens avenues for creating proteases with enhanced catalytic efficiency and novel regulatory mechanisms.