Structural analysis of a prototypical ATPase from the type III secretion system

Area of Science:

• Microbiology
• Structural Biology
• Molecular Biology

Background:

• The type III secretion system (T3SS) is essential for bacterial virulence, mediating the delivery of effector proteins into host cells.
• The T3SS ATPase is a key inner-membrane component responsible for initiating this secretion process.

Purpose of the Study:

• To elucidate the structure and function of the T3SS ATPase, EscN, from enteropathogenic Escherichia coli (EPEC).
• To understand the molecular basis of effector protein secretion and bacterial pathogenicity.

Main Methods:

• 1.8-Å resolution crystal structure determination of the EscN catalytic domain.
• In vitro and in vivo mutational analyses.
• Biochemical assays to assess ATPase activity and oligomerization.

Main Results:

• The crystal structure of the EscN catalytic domain was determined at 1.8-Å resolution.
• T3SS ATPases share structural similarities with F1 ATPases but possess distinct features crucial for their secretory function.
• EscN ATPase activity is dependent on its oligomerization, forming a hexameric ring structure.

Conclusions:

• The structural and functional characterization of EscN provides insights into the mechanism of T3SS-mediated protein secretion.
• The hexameric ring model of EscN offers a molecular basis for its role in initiating effector protein translocation.
• Understanding T3SS ATPase function is critical for developing novel anti-virulence strategies against pathogenic bacteria.