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- MPI für Biophysik (2)
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- MPI für Hirnforschung (1)
- CryoEM structures of membrane pore and prepore complex reveal cytolytic mechanism of Pneumolysin (2017)
- Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor of Streptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain 3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel. The apolar outer barrel surface with large sidechains is immersed in the lipid bilayer, while the inner barrel surface is highly charged. Comparison of the cryoEM pore complex to the prepore structure obtained by electron cryo-tomography and the x-ray structure of the soluble form reveals the detailed mechanisms by which the toxin monomers insert into the lipid bilayer to perforate the target membrane.
- "Awakening Asia" : Korean student activists in Japan, The Asia Kunglun, and Asian solidarity, 1910-1923 (2017)
- The contributions of Korean and Taiwanese authors to the many and varied formulations of interwar pan-Asianism have so far remained a relatively unexplored subject of scholarly research, despite an unbroken interest in the trajectory of state-based Japanese pan-Asianism. Focusing on Korean students and independence activists, this article discusses alternative configurations of regional unity and solidarity that emanated from the interactions among Korean, Taiwanese, and other Asian actors who resided in Tokyo during the 1910s and 1920s. When the ethnic-nationalist interpretations of the Wilsonian principle of self-determination failed to materialize, a portion of anti-colonial activists in Asia began to emphasize the need for solidarity by drawing on what they perceived as traditional and shared “Asian” values. While challenging the Western-dominated international order of nation-states that perpetuated imperialism, such notions of Asian solidarity at the same time served as an ideology of liberation from Japanese imperialism. Examining journals published by Korean students and activists, including The Asia Kunglun, this article adds another layer to the history of pan-Asianism from below, a perspective that has often been neglected within the larger context of scholarship on pan-Asianism and Japanese imperialism in Asia.
- Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium (2020)
- Type IV pili are flexible filaments on the surface of bacteria, consisting of a helical assembly of pilin proteins. They are involved in bacterial motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Here, we use cryo-electron microscopy and mass spectrometry to show that the bacterium Thermus thermophilus produces two forms of type IV pilus ("wide" and "narrow"), differing in structure and protein composition. Wide pili are composed of the major pilin PilA4, while narrow pili are composed of a so-far uncharacterized pilin which we name PilA5. Functional experiments indicate that PilA4 is required for natural transformation, while PilA5 is important for twitching motility.
