Structural basis for pore-forming mechanism of staphylococcal α-hemolysin

Takaki Sugawara, Daichi Yamashita, Koji Kato, Zhao Peng, Junki Ueda, Jun Kaneko, Yoshiyuki Kamio, Yoshikazu Tanaka, Min Yao

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Staphylococcal α-hemolysin (α-HL) is a β-barrel pore-forming toxin (PFT) expressed by Staphylococcus aureus. α-HL is secreted as a water-soluble monomeric protein, which binds to target membranes and forms membrane-inserted heptameric pores. To explore the pore-forming mechanism of α-HL in detail, we determined the crystal structure of the α-HL monomer and prepore using H35A mutant and W179A/R200A mutant, respectively. Although the overall structure of the monomer was similar to that of other staphylococcal PFTs, a marked difference was observed in the N-terminal amino latch, which bent toward the prestem. Moreover, the prestem was fastened by the cap domain with a key hydrogen bond between Asp45 and Tyr118. Prepore structure showed that the transmembrane region is roughly formed with flexibility, although the upper half of the β-barrel is formed appropriately. Structure comparison among monomer, prepore and pore revealed a series of motions, in which the N-terminal amino latch released upon oligomerization destroys its own key hydrogen bond between Asp45-Tyr118. This action initiated the protrusion of the prestem. Y118F mutant and the N-terminal truncated mutant markedly decreased in the hemolytic activity, indicating the importance of the key hydrogen bond and the N-terminal amino latch on the pore formation. Based on these observations, we proposed a dynamic molecular mechanism of pore formation for α-HL.

Original languageEnglish
Pages (from-to)226-231
Number of pages6
JournalToxicon
Volume108
DOIs
Publication statusPublished - Dec 15 2015
Externally publishedYes

Keywords

  • Crystal structure
  • Pore-forming toxin
  • Staphylococcal α-hemolysin

ASJC Scopus subject areas

  • Toxicology

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  • Cite this

    Sugawara, T., Yamashita, D., Kato, K., Peng, Z., Ueda, J., Kaneko, J., Kamio, Y., Tanaka, Y., & Yao, M. (2015). Structural basis for pore-forming mechanism of staphylococcal α-hemolysin. Toxicon, 108, 226-231. https://doi.org/10.1016/j.toxicon.2015.09.033