Biogenesis and structure of a type VI secretion baseplate

Area of Science:

• Microbiology
• Structural Biology
• Bacterial Pathogenesis

Background:

• Bacteria utilize macromolecular machines for effector and toxin delivery, crucial for growth and pathogenesis.
• The type VI secretion system (T6SS) is a contractile nanomachine that injects substances into prokaryotic and eukaryotic cells.
• The T6SS structure includes a tail, sheath, inner tube, baseplate, and membrane complex, with the baseplate acting as an evolutionary adaptor.

Purpose of the Study:

• To define the biogenesis pathway of the T6SS baseplate.
• To determine the cryo-electron microscopy (cryo-EM) structure of the T6SS wedge protein complex.
• To unveil the molecular architecture of the T6SS baseplate and its interaction with the tail sheath.

Main Methods:

• Cryo-electron microscopy (cryo-EM)
• Integrative structural biology approaches
• Biochemical and genetic analyses (implied)

Main Results:

• Defined the biogenesis pathway of the T6SS baseplate.
• Reported the cryo-EM structure of the T6SS wedge protein complex from enteroaggregative Escherichia coli (EAEC).
• Unveiled the molecular architecture of the T6SS baseplate and its interaction with the tail sheath.

Conclusions:

• The study provides detailed insights into the biogenesis and function of the T6SS baseplate.
• Key architectural and mechanistic similarities and differences were identified compared to T4 and Mu phage baseplates.
• This work advances our understanding of bacterial secretion systems and their role in pathogenesis.