期刊
NATURE STRUCTURAL & MOLECULAR BIOLOGY
卷 29, 期 12, 页码 1170-+出版社
NATURE PORTFOLIO
DOI: 10.1038/s41594-022-00868-7
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资金
- Swiss National Science Foundation (SNSF) [310030B_201273]
- SNSF National Centres of Competence in Research (NCCR) AntiResist [180541]
- SNSF NCCR TransCure [185544]
- Chinese Scholarship Council [201709370040]
- Swiss National Science Foundation (SNF) [310030B_201273] Funding Source: Swiss National Science Foundation (SNF)
Polysaccharides play critical roles in bacteria and their transport is mediated by ATP-binding cassette (ABC) transporters. This study used cryoelectron microscopy to elucidate the structures of Cgt from Brucella abortus and revealed the binding mode and substrate release mechanism, providing insights into the translocation of large substrates and protein-polysaccharide interactions.
Polysaccharides play critical roles in bacteria, including the formation of protective capsules and biofilms and establishing specific host cell interactions. Their transport across membranes is often mediated by ATP-binding cassette (ABC) transporters, which utilize ATP to translocate diverse molecules. Cyclic beta-glucans (C beta Gs) are critical for host interaction of the Rhizobiales, including the zoonotic pathogen Brucella. C beta Gs are exported into the periplasmic space by the cyclic glucan transporter (Cgt). The interaction of an ABC transporter with a polysaccharide substrate has not been visualized so far. Here we use single-particle cryoelectron microscopy to elucidate the structures of Cgt from Brucella abortus in four conformational states. The substrate-bound structure reveals an unusual binding pocket at the height of the cytoplasmic leaflet, whereas ADP-vanadate models hint at an alternative mechanism of substrate release. Our work provides insights into the translocation of large, heterogeneous substrates and sheds light on protein-polysaccharide interactions in general.
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