Why Study PCPs?
Polysaccharide co-polymerases (PCPs) are large membrane protein complexes responsible for determining how long a lipopolysaccharide (LPS) molecule is made, before it is inserted into the outer membrane of a bacterial cell. The LPS on the surface of different bacteria have different average lengths, and this is important because it is involved in how the cell prevents unwanted things entering the cell, or how it evades detection by the immune system. If we can understand how this membrane complex is able to influence how long a LPS molecule is made, it would then be possible to disrupt it to our advantage.
What Do PCPs Do?
We do not yet know how PCPs determine LPS length. Possible theories are that it acts as a molecular stopwatch, or a ruler, but a more detailed picture of the structure of this protein complex in its natural conformation would assist in figuring out how it works. Electron microscopy of the native protein complex of WzzE isolated from the membrane revealed a larger nonomer, although the exact number of monomers has not yet been determined.
I was also able to grow crystals of WzzE that diffracted to 10Å, and can hopefully be improved upon to allow the dertemination of the crystal structure of the protein as a native complex.