The structure of a Lactobacillus helveticus chlorogenic acid esterase and the dynamics of its insertion domain provide insights into substrate binding

Chlorogenic acid esterases (ChlEs) are a useful class of enzymes that hydrolyze chlorogenic acid (CGA) into caffeic and quinic acids. ChlEs can break down CGA in foods to improve their sensory properties and release caffeic acid in the digestive system to improve the absorption of bioactive compounds. This work presents the structure, molecular dynamics, and biochemical characterization of a ChlE from Lactobacillus helveticus (Lh). Molecular dynamics simulations suggest that substrate access to the active site of LhChlE is modulated by two hairpin loops above the active site. Docking simulations and mutational analysis suggest that two residues within the loops, Gln(145) and Lys(164), are important for CGA binding. Lys(164) provides a slight substrate preference for CGA, whereas Gln(145) is required for efficient turnover. This work is the first to examine the dynamics of a bacterial ChlE and provides insights on substrate binding preference and turnover in this type of enzyme.

Automated summary

This study examines the structure, dynamics, and biochemical characteristics of a chlorogenic acid esterase (ChlE) from Lactobacillus helveticus. The results indicate that the access of substrates to the active site of the enzyme is regulated by hairpin loops, and two amino acid residues, Gln(145) and Lys(164), are crucial for chlorogenic acid binding and turnover.