Regulatory Effect of Transcriptional Regulator TetR on the Synthesis of Conjugated Linoleic Acid in Lactiplantibacillus plantarum AR195

Conjugated linoleic acid (CLA) possesses anticancer, anti-inflammatory, and antiobesity properties, making it a significant research focus. In this study, we identified TetR, a TetR/AcrR family transcriptional regulator encoded by AR1031, as the transcriptional regulator of CLA synthesis in Lactiplantibacillus plantarum AR195. TetR binds to the promoter regions of the CLA synthesis genes, including the cla operon and cla-hy, thereby enhancing CLA biosynthesis. Knockout of tetR led to the downregulation of cla-hy by 68%, cla-dh by 86%, and cla-dc by 33%, resulting in reduced CLA yield. Further bioinformatic analysis and segmented electrophoretic mobility shift assay (EMSA) experiments revealed that TetR recognizes a conserved sequence (5'-TGTAGATTG-n₄-CTTCA-3') and binds to multiple sites within the regulatory region of the cla operon and cla-hy, thus promoting CLA biosynthesis. Overexpression of tetR increased the CLA yield by 7%. These findings provide precise insights into the regulation of CLA biosynthesis and suggest strategies for enhancing CLA production.