Journal of Biological Chemistry
Volume 290, Issue 51, 18 December 2015, Pages 30204-30211
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Recognition of Vitamin B Precursors and Byproducts by Mucosal Associated Invariant T Cells*

https://doi.org/10.1074/jbc.R115.685990Get rights and content
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Vitamin B2 (riboflavin) is essential for metabolic functions and is synthesized by many bacteria, yeast, and plants, but not by mammals and other animals, which must acquire it from the diet. In mammals, modified pyrimidine intermediates from the microbial biosynthesis of riboflavin are recognized as signature biomarkers of microbial infection. This recognition occurs by specialized lymphocytes known as mucosal associated invariant T (MAIT) cells. The major histocompatibility class I-like antigen-presenting molecule, MR1, captures these pyrimidine intermediates, but only after their condensation with small molecules derived from glycolysis and other metabolic pathways to form short-lived antigens. The resulting MR1-Ag complexes are recognized by MAIT cell antigen receptors (αβ T cell receptors (TCRs)), and the subsequent MAIT cell immune responses are thought to protect the host from pathogens at mucosal surfaces. Here, we review our understanding of how these novel antigens are generated and discuss their interactions with MR1 and MAIT TCRs.

bacterial metabolism
folate
innate immunity
riboflavin
vitamin
Ag presentation
MAIT cells
MR1
T cell recognition

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*

This work was supported by Australian Research Council Grants E140100011 and LE110100106 and National Health and Medical Research Council (NHMRC) of Australia Grants 1016629, 1013667, 1062889, and 1063587. The authors declare that they have no conflicts of interest with the contents of this article.

1

These authors contributed equally to this work.

2

Supported by an Early Career Researcher award from The University of Melbourne.

3

NHMRC Senior Principal Research Fellows.