A new method to visualize the Helicobacter pylori-associated Lewis- binding adhesin utilizing SDS-digested freeze-fracture replica labeling

Freeze-fracture replica labeling has become a versatile tool to visualize both membrane components and other cell structures using SDS- replica cleaning before specific immunogold labeling of proteins or lipids. We report here for the first time the adoption and optimization of the method to studies of bacterial envelopes, as applied to structural analysis of the distribution of the unique BabA-adhesin of the gastric pathogen Helicobacter pylori. BabA is important for bacterial adherence to the human epithelial cell lining of the stomach. The adhesin was found to be distributed all over the bacterial cell surfaces. Our results suggest that the SDS-replica labeling allows assessment of protein localization to distinct cell compartments and analysis of co-localization with neighboring membrane structures.