周质间隙
ATP结合盒运输机
运输机
生物化学
布鲁氏菌
化学
葡聚糖
生物
细菌外膜
细胞生物学
生物物理学
大肠杆菌
基因
病毒学
布鲁氏菌病
作者
Jarosław Sędzicki,Dongchun Ni,Frank Serge Lehmann,Na Wu,Renato Zenobi,Seunho Jung,Henning Stahlberg,Christoph Dehio
标识
DOI:10.1038/s41594-022-00868-7
摘要
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 β-glucans (CβGs) are critical for host interaction of the Rhizobiales, including the zoonotic pathogen Brucella. CβGs 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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