Structure of a full-length bacterial polysaccharide co-polymerase

Area of Science:

• Structural Biology
• Microbiology
• Biochemistry

Background:

• Lipopolysaccharides are crucial bacterial cell envelope components, acting as protective barriers.
• The Wzy-dependent pathway is a widespread mechanism for polysaccharide biosynthesis in bacteria.

Purpose of the Study:

• To determine the 3.0 Å structure of WzzB, the co-polymerase component of the Wzy-dependent pathway.
• To elucidate the architecture of WzzB and its transmembrane domain.

Main Methods:

• Single-particle cryo-electron microscopy was employed to solve the structure of WzzB from E. coli.

Main Results:

• The study presents the octameric structure of WzzB, resembling a box jellyfish.
• A large, bell-shaped periplasmic domain and a 2-helix transmembrane domain encircling a transmembrane chamber were identified.
• The structure reveals key residues within the transmembrane domain relevant to Wzz-family proteins and the Wzy-dependent pathway.

Conclusions:

• The determined structure provides insights into the Wzy-dependent pathway's mechanism.
• This work explains previous biochemical and mutational studies on WzzB.
• The findings lay the groundwork for future research into bacterial cell envelope biosynthesis and antibiotic resistance.