A team of researchers working at SSRL has determined the atomic structure of an assemblage of fiber-forming proteins found in the cell membranes of many dangerous types of bacteria. The protein, called pilin, assembles into filamentous organelles called Type IV pili found on the surfaces of most Gram-negative bacteria. Type IV pili plays a central role in how these bacterial pathogens infect a host and are involved in cellular functions such as motility, adhesion, microcolony formation and uptake of DNA and specific filamentous phage.

John Tainer and colleagues at The Scripps Research Institute succeeded in solving the crystal structures of T4P from several important human pathogens using the macromolecular crystallography beam lines at SSRL (BLs 7-1, 9-1, 9-2 and 11-1). Membrane proteins are notoriously difficult to crystallize, and fiber-forming proteins were actually once declared "uncrystallizable" by the eminent x-ray crystallographer Sir Lawrence Bragg.

The prominent exposure of T4P on bacterial surfaces and their key functions in virulence make T4P attractive targets for vaccines and therapeutics. Detailing the molecular structure of T4P will greatly benefit the design of drugs that target these structures.

To learn more about this research see the full scientific highlight at:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/pilin.html

Craig, L. et al. Type IV Pilus Structure by Cryo-Electron Microscopy and Crystallography: Implications for Pilus Assembly and Functions. Molecular Cell 23, 651-662 (2006).