Modification of chimeric (2S, 3S)-butanediol dehydrogenase based on structural information

Area of Science:

• Biochemistry
• Enzyme Engineering
• Structural Biology

Background:

• Chimeric butanediol dehydrogenase (BDH) engineered for stability and specificity.
• Native enzymes (2S, 3S)-BDH from Brevibacterium saccharolyticum and (2R, 3S)-BDH from Klebsiella pneumonia used as templates.
• Engineered enzyme (cLBDH) combined stability of KpMBDH with specificity of BsLBDH, but lacked strict specificity.

Purpose of the Study:

• To understand the structural basis for specificity differences between cLBDH and BsLBDH.
• To design a novel (2S, 3S)-BDH with preferred specificity.
• To utilize X-ray crystallography for guiding enzyme engineering.

Main Methods:

• Engineering of a chimeric butanediol dehydrogenase (cLBDH) by domain swapping.
• X-ray structural analysis of cLBDH crystal at 1.58 Å resolution.
• Site-directed mutagenesis (V254L) based on structural insights.

Main Results:

• Identified significant differences in the active sites of cLBDH and BsLBDH via X-ray crystallography.
• Developed a novel (2S, 3S)-BDH variant with improved specificity through a V254L mutation.
• Demonstrated the effectiveness of structure-guided design for creating tailor-made BDHs.

Conclusions:

• X-ray structural analysis is crucial for understanding enzyme active site differences.
• A V254L mutation in cLBDH enhances specificity for (2S, 3S)-butanediol.
• This approach enables the rational design of enzymes with desired substrate specificities.