The LptC transmembrane helix undergoes a rigid body movement upon LptB₂FG cavity collapse

Protein Science, Год журнала: 2025, Номер 34(5)

Опубликована: Апрель 22, 2025

Abstract Lipopolysaccharide (LPS) is an essential component of the cellular envelope Gram‐negative bacteria and contributes to antibiotic resistance pathogenesis. Proper localization LPS at outer membrane facilitated via seven distinct transport (Lpt) proteins that bridge inner membranes. Mature diffuses into cavity ABC transporter LptB 2 FGC through a lateral gate formed by LptF LptG transmembrane (TM) helices. The TM helix LptC intercalates within entry point has been shown regulate ATPase activity FG contribute thermal stability. Determination open state structure revealed location complex. However, in closed structure, unresolved, suggesting may be displaced from prior or upon closure cavity. To determine conformational states conformations, we utilized site‐directed spin labeling combination with both continuous wave electron paramagnetic resonance (EPR) double (DEER) spectroscopies investigate linker region. These data indicate undergoes rigid body movement away central closure. findings presented here will support structure‐based drug design optimization recently discovered antibiotics bind occlude gate.

Язык: Английский

Dynamic basis of lipopolysaccharide export by LptB2FGC

eLife, Год журнала: 2024, Номер 13

Опубликована: Июль 1, 2024

Lipopolysaccharides (LPS) confer resistance against harsh conditions, including antibiotics, in Gram-negative bacteria. The lipopolysaccharide transport (Lpt) complex, consisting of seven proteins (A-G), exports LPS across the cellular envelope. LptB 2 FG forms an ATP-binding cassette transporter that transfers to LptC. How couples ATP binding and hydrolysis with LptC remains unclear. We observed conformational heterogeneity FGC micelles and/or proteoliposomes using pulsed dipolar electron spin resonance spectroscopy. Additionally, we monitored release laser-induced liquid bead ion desorption mass spectrometry. β-jellyroll domain LptF stably interacts LptG β-jellyrolls both apo vanadate-trapped states. at cytoplasmic side is allosterically coupled selective opening periplasmic domain. In FG, closes nucleotide domains, causing a collapse first lateral gate as structures. However, second gate, which putative entry site for LPS, exhibits heterogeneous conformation. limits flexibility this two conformations, likely representing helix either released from or inserted into transmembrane domains. Our results reveal regulation through dynamic behavior helix, while its anchored periplasm. This, combined long-range ATP-dependent allosteric gating domain, may ensure efficient unidirectional

Язык: Английский