Crystallization and preliminary X-ray diffraction analysis of PsaA, the adhesive pilin subunit that forms the pH 6 antigen on the surface of Yersinia pestis

The pH 6 antigen Psa displayed on the surface of Yersinia pestis, the bacterium that causes plague in humans, consists of polymers of a single protein subunit termed PsaA. Donor-strand complemented PsaA was purified and crystallized.