Synthesis of Bacterial Cell Wall Fragments

The bacterial cell wall, peptidoglycan, is a highly conserved structure found in all bacteria. Peptidoglycan
is a mesh-like carbohydrate polymer that provides the mechanical support necessary to prevent the cells
from bursting as the osmotic pressure fluctuates. Humans do not have bacterial cell walls and thus it
makes an ideal structure for our innate immune systems to recognize the presence of bacteria.

It has long been known that small fragments of bacterial cell wall, such as muramyl dipeptide (see
figure) are able to stimulate an immune response. In order to identify the receptors of these molecules,
we use chemical synthesis to construct a variety of probes. The ability to design and synthesize a host of
immunostimulatory molecules with a variety of functionalities gives us a set of unique tools to dissect
innate immune signaling.