PT  - JOURNAL ARTICLE
AU  - Mònica Santiveri
AU  - Aritz Roa-Eguiara
AU  - Caroline Kühne
AU  - Navish Wadhwa
AU  - Howard C. Berg
AU  - Marc Erhardt
AU  - Nicholas M. I. Taylor
TI  - Structure and function of stator units of the bacterial flagellar motor
AID  - 10.1101/2020.05.15.096610
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.15.096610
4099  - http://biorxiv.org/content/early/2020/05/15/2020.05.15.096610.short
4100  - http://biorxiv.org/content/early/2020/05/15/2020.05.15.096610.full
AB  - Many bacteria use the flagellum for locomotion and chemotaxis. Its bi-directional rotation is driven by the membrane-embedded motor, which uses energy from the transmembrane ion gradient to generate torque at the interface between stator units and rotor. The structural organization of the stator unit (MotAB), its conformational changes upon ion transport and how these changes power rotation of the flagellum, remain unknown. Here we present ~3 Å-resolution cryo-electron microscopy reconstructions of the stator unit in different functional states. We show that the stator unit consists of a dimer of MotB surrounded by a pentamer of MotA. Combining structural data with mutagenesis and functional studies, we identify key residues involved in torque generation and present a mechanistic model for motor function and switching of rotational direction.One Sentence Summary Structural basis of torque generation in the bidirectional bacterial flagellar motorCompeting Interest StatementThe authors have declared no competing interest.