Rational design of disulfide bonds to increase thermostability of Rhodococcus opacus catechol 1,2 dioxygenase

Area of Science:

• Biochemistry
• Protein Engineering
• Enzyme Technology

Background:

• Catechol 1,2 dioxygenase is a valuable enzyme with broad industrial potential.
• Low thermostability limits the practical applications of this enzyme.
• Enhancing enzyme stability is crucial for industrial biocatalysis.

Purpose of the Study:

• To improve the thermostability of mesophilic catechol 1,2 dioxygenase from Rhodococcus opacus.
• To engineer disulfide bonds into the enzyme structure to enhance thermal stability.
• To evaluate the effectiveness of computational prediction in designing thermostabilized enzymes.

Main Methods:

• Computational prediction was used to design 56 potential disulfide bond introductions.
• Selection criteria narrowed down designs to 9 candidates for experimental validation.
• Recombinant production and purification of engineered variants were performed.
• Thermostability assays (T50, half-life, Tm) and activity measurements (turnover number) were conducted.

Main Results:

• Several engineered variants showed significantly enhanced protein thermostability.
• Variant K96C-D278C exhibited a 4.6°C increase in T50 and a 5.5°C increase in Tm.
• This variant also demonstrated a 725% increase in half-life and a >10-fold increase in total turnover number.
• Combining multiple design improvements (stacking) was not effective.

Conclusions:

• Computational prediction algorithms are effective for designing disulfide-thermostabilized catechol 1,2 dioxygenase.
• Engineered catechol 1,2 dioxygenase variants show substantial improvements in thermostability and activity.
• This work overcomes limitations of enzyme stability for industrial applications.