A world first! Clarification of the structure of Shigella secretion needle
a step in the development of drugs not producing drug-resistant bacteria
Under the leadership of FUJII Takashi , Researcher, KATO Takayuk i, Assistant professor, and NAMBA Keiichi , Professor, of the Graduate School of Frontier Biosciences, Osaka University, and Ariel Blocker Group, University of Bristol, a group of researchers succeeded in clarifying the high resolution steric structure of a needle in Shigella using the latest technology of cryo electron microscopy.
Shigella injects pathogenic factors into host cells using a syringe-like protein secretion structure referred to as a needle. As the needle of Shigella flexneri is a mere 7-nm thick and is a helical assembly of one protein, MxiH, its structural analysis was very difficult.
This group has clarified how such such a thin tubular structure is stably assembled and pathogenic factors pass through the needle's channel of approximately 1.3 nm in diameter unfolded.
The group has also clarified how the needle-length control protein functions within the central channel during export of MxiH for assembly at the distal end of the needle, and how the secretion-activation signal may be transduced through a conformational change in the needle upon host-cell contact.
The clarification of the steric structure of the needle complex is of great help in the clarification of the initial process of infection and will greatly aid the development of new drugs based on the structure.
Additionally, it may become possible to develop infection-control drugs that prevent the secretion of pathogenicity factors. As these drugs are innoxious to bacteria themselves, the emergence of resistant bacteria can be prevented.
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To learn more about this important discovery, please read the full research report entitled " TStructure of a type III secretion needle at 7-Å resolution provides insights into its assembly and signaling mechanisms " at this page at the PNAS website.
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