Structural and Functional Characterization of Conserved Key Amino Acids in Lipoteichoic Acid Synthase LtaS of Lactiplantibacillus plantarum

Lipoteichoic acid synthase (LtaS) is crucial for the biosynthesis of lipoteichoic acid (LTA) in lactic acid bacteria (LAB), where LTA plays a key role in bacterial adhesion, immune modulation, and maintaining cell integrity. This study explores the regulation of LtaS activity in Lactiplantibacillus plantarum, examining the effects of factors such as temperature, pH, and metal ions on enzyme activity. Molecular docking was used to identify critical amino acids at the enzyme's active site, and site-directed mutagenesis confirmed the role of five key residues (Glu-259, Thr-303, Asn-353, Arg-360, and His-420) in LtaS activity. Among them, Thr-303 plays a pivotal role, followed by Glu-259 and His-420. Conservation analysis revealed that these active-site residues are highly conserved across LAB species. These findings provide valuable insights into the functional properties of LtaS, offering potential for enhancing the efficacy of LAB-based probiotics and improving their therapeutic benefits in health applications.