Dynamic signature of activity-stability tradeoff in lactamase evolution

Area of Science:

• Biochemistry
• Structural Biology
• Evolutionary Biology

Background:

• Understanding protein evolution requires knowledge of how evolutionary landscapes are shaped at the protein level.
• The TEM-1 β-lactamase enzyme system provides a model for studying protein adaptation and the evolution of drug resistance.

Purpose of the Study:

• To investigate the role of protein structural ensembles in shaping evolutionary landscapes.
• To elucidate the mechanisms by which mutations confer cefotaxime resistance in TEM-1 β-lactamase.

Main Methods:

• Utilized TEM-1 β-lactamase as a model system.
• Analyzed molecular traits related to protein structure and conformational ensembles.
• Studied the impact of mutations on substrate specificity, active site-scaffold communication, and stabilizing substitutions.

Main Results:

• The statistical ensemble nature of protein structure influences substrate specificity and active site-scaffold communication.
• Initial mutations reorganize the active site into a new functional conformation, while secondary mutations restore catalytic efficiency by redistributing conformational ensembles.
• Stability defects are clustered in specific scaffold elements, and mutations modulate active site and scaffold populations, leading to conformational epistasis and compensation.

Conclusions:

• Protein structural ensembles are critical for understanding protein evolution and adaptation.
• The evolution of drug resistance involves complex interplay between mutations affecting protein conformation and stability.
• Conformational epistasis allows for local compensation of stability defects, facilitating the acquisition of new functions.