Pathogenic bacteria secrete pore-forming toxins (PFTs) to attack target cells. PFTs are expressed as water-soluble monomeric proteins, which oligomerize into nonlytic prepore intermediates on the target cell membrane before forming membrane-spanning ...
Pathogenic bacteria secrete pore-forming toxins (PFTs) to attack target cells. PFTs are expressed as water-soluble monomeric proteins, which oligomerize into nonlytic prepore intermediates on the target cell membrane before forming membrane-spanning pores. Despite a wealth of biochemical data, the lack of high-resolution prepore structural information has hampered understanding of the β-barrel formation process. Here, we report crystal structures of staphylococcal γ-haemolysin and leucocidin prepores. The structures reveal a disordered bottom half of the β-barrel corresponding to the transmembrane region, and a rigid upper extramembrane half. Spectroscopic analysis of fluorescently labelled mutants confirmed that the prepore is distinct from the pore within the transmembrane region. Mutational analysis also indicates a pivotal role for the glycine residue located at the lipid-solvent interface as a 'joint' between the two halves of the β-barrel. These observations suggest a two-step transmembrane β-barrel pore formation mechanism in which the upper extramembrane and bottom transmembrane regions are formed independently.
Organizational Affiliation:
Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.,Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, Yurigaoka 4-10-1, Natori 981-1295, Japan.,1] Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan [2] Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.,Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
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