Structural basis for regulating lipopolysaccharide transmembrane transport.

LPS transport in Gram-negative bacteria is regulated by Lpt bridge assembly, which activates ATP hydrolysis through movement of TM-LptC in response to LPS presence.

• Why it matters: Understanding how LPS translocation is controlled is crucial because it influences bacterial resistance to antibiotics and cell envelope integrity, yet the regulation mechanism was previously unclear.
• What they did: The study determined three structures of the Lpt complex in different states and a partial bridge, combined with biochemical experiments, revealing how LPS-dependent conformational changes regulate transport activity.
• The result: Findings demonstrate that Lpt bridge assembly and TM-LptC movement coordinate LPS transport with inner membrane LPS levels, providing insight into bacterial outer membrane biogenesis and potential targets for antibiotic development.