Fig. 1: Microbial phosphorothioate (PT) DNA modifications.
From: Phosphorothioate DNA modification by BREX type 4 systems in the human gut microbiome
A Sulfur replaces a non-bridging phosphate oxygen in the DNA backbone in PT modifications. A limit nuclease digest of PT-containing DNA leaves PT-linked dinucleotides that can be identified and quantified by LC–MS. B Synthesis of PTs generally follows the biochemical steps performed by Dnd proteins.
