Major histocompatibility complex class I-related protein (MR1) and pyridoxine-dependent enzymes (MR1/PLP-dependent enzymes)

This target entry represents a functional grouping of the Major Histocompatibility Complex Class I-Related Protein (MR1) and the broad class of enzymes that require pyridoxine (Vitamin B6) derivatives as cofactors. MR1 is a non-polymorphic antigen-presenting molecule that captures small molecule metabolites, primarily derived from microbial riboflavin (Vitamin B2) synthesis, and presents them to Mucosal-Associated Invariant T (MAIT) cells to initiate an immune response against pathogens like Mycobacterium tuberculosis (Keller et al., 2014, Nature). Pyridoxine-dependent enzymes, such as aromatic L-amino acid decarboxylase and cystathionine beta-synthase, are essential for neurotransmitter synthesis and amino acid metabolism. The intersection of these two entities is clinically significant because several drugs, most notably the anti-tuberculosis medication isoniazid, act as antagonists to pyridoxine-dependent enzymes, leading to side effects like peripheral neuropathy, while also potentially modulating the MR1-MAIT cell axis (Keller et al., 2012, Science). This grouping is often used in the context of drug-induced metabolic interference and immunomodulation during the treatment of infectious diseases.

Other names

MHC class I-related gene proteinClass I-related antigen MR1Pyridoxal 5'-phosphate-dependent enzymesPLP-dependent enzymesVitamin B6-dependent enzymes

MR1 presents microbial vitamin B2-derived metabolites to MAIT cells to trigger immune responses; pyridoxine-dependent enzymes utilize PLP as a cofactor for various metabolic reactions, and certain drugs inhibit these enzymes or deplete PLP levels.