An in vitro assay of the effect of lysine oxidation end-product, α-aminoadipic acid, on the redox status and gene expression in probiotic Lactobacillus reuteri PL503

• Published in: Amino acids Vol. 54; no. 4; pp. 663 - 673
• Main Authors: Padilla, Patricia, Andrade, María J., Peña, Fernando J., Rodríguez, Alicia, Estévez, Mario
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.04.2022; Springer Nature B.V
• Subjects: Amino acids; Analytical Chemistry; Antioxidants; Bacteria; Biochemical Engineering; Biochemistry; Biomedical and Life Sciences; Carbonyls; Deposition; Food; Gene expression; Lactobacillus reuteri; Life Sciences; Lysine; Neurobiology; Original; Original Article; Oxidation; Oxidative stress; Post-translation; Post-translational modifications (PTM); Probiotics; Proteins; Proteomics; Reactive oxygen species; UspA gene; Oxidative stress; Oxidized amino acids; Protein oxidation; Probiotic bacterium; Transcripts
• ISSN: 0939-4451; 1438-2199
• DOI: 10.1007/s00726-021-03087-4

This study was designed to gain information about the underlying mechanisms of the effects of a food-occurring free oxidized amino acid, α-aminoadipic acid (AAA), on the probiotic Lactobacillus reuteri PL503. This bacterium was incubated in colonic-simulated conditions (37 °C for 24 h in microaerophilic conditions) and exposed to three food-compatible AAA concentrations, namely, 1 mM, 5 mM, and 10 mM. A control group with no AAA exposure was also considered. Each of the four experimental conditions was replicated three times and samplings were collected at 12, 16, 20, and 24 h. The downregulation of the uspA gene by AAA (0.5-fold decrease as compared to control) suggests that AAA is identified as a potential chemical threat. The dhaT gene, implicated in the antioxidant defense, was found to be upregulated in bacteria treated with 1 and 5 mM AAA (up to twofold increase, as compared to control), which suggest the ability of the oxidized amino acid to impair the redox status of the bacterium. In fact, AAA caused an increased production of reactive oxygen species (ROS) and the accretion of post-translational changes (protein carbonylation) in L. reuteri (up to 13 nmol allysine/mg protein vs 1.8 nmol allysine/mg protein in control). These results suggest that probiotic bacteria identify oxidized amino acids as harmful species and activate mechanisms that may protect themselves and the host against their noxious effects.