Identification of 4-hydroxy-3-methyl-but-2-enyl pyrophosphate as a major activator for human gamma delta T cells in Escherichia coli

Abstract

The gcpE and lytB gene products control the terminal steps of isoprenoid biosynthesis via the 2-C-methyl-Image -erythritol 4-phosphate pathway in Escherichia coli. In lytB-deficient mutants, a highly immunogenic compound accumulates significantly, compared to wild-type E. coli, but is apparently absent in gcpE-deficient mutants. Here, this compound was purified from E. coli ΔlytB mutants by preparative anion exchange chromatography, and identified by mass spectrometry, 1H, 13C and 31P NMR spectroscopy, and NOESY analysis as (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP). HMB-PP is 104 times more potent in activating human Vγ9/Vδ2 T cells than isopentenyl pyrophosphate.