Synthesis of Artificial Bacterial Cell Wall Fragments as Tools to Study the Innate Immune System

Abstract

During a bacterial infection, the body's first line of defense is provided by the innate immune system. This system is triggered by pathogen‐associated molecular patterns (PAMPs) that are recognized by different members of the body's innate immune system called pattern recognition receptors (PRRs). One such PRR of interest is nucleotide‐binding oligomerization domain‐containing protein 2 (Nod2). Mammalian Nod2 is a cytosolic protein that binds to and signals in response to carbohydrate containing bacterial cell wall fragments; the smallest of which is muramyl dipeptide (MDP). Mutations in Nod2 increase the likelihood of the development of Crohn's Disease and other chronic inflammatory diseases. Previously, our lab has shown that Nod2 binds directly to MDP, but currently the molecular mechanisms of activation and binding are still unknown1. Currently, we are addressing this issue using synthetic chemistry. This project focuses on the synthesis of an assortment of MDP dimers, which vary in the length and functionality of their connecting linkers. To avoid troublesome late‐stage de‐protection issues, the synthesis diverges in its early stages to result in two differing MDP‐like fragments. These two fragments can then be coupled together and de‐protected, resulting in the MDP dimer. Once synthesized, these dimers will be used in in vitro SPR binding assays, as well as in cell‐based assays to elucidate the binding and activation mechanisms used by Nod2. Ultimately, these synthetic tools will aid in the advancement of our understanding of how are body's sense and respond to bacteria.Support or Funding InformationHoward Hughes Medical Institute