2015/01/13 by Kranthi K. Mandadapu, Jasmine A. Nirody, Richard M. Berry +1 · 65 citations
Biochemistry, Genetics and Molecular Biology · Chemistry · Engineering · Physics and Astronomy · #Biology #Biophysics #Chemistry #Computer science #Control theory (sociology) #Lipid Membrane Structure and Behavior #Micro and Nano Robotics #Microfluidic and Bio-sensing Technologies #Molecular motor #Physics #Stator #Torque #physics.bio-ph #q-bio.SC
paper · pdf · doi:10.1073/pnas.1501734112
published in Proceedings of the National Academy of Sciences 112(32), E4381-9 (National Academy of Sciences)
arxiv created 2015/01/13 · openalex publication_date 2015/07/27 · arxiv updated 2016/02/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well established that the passage of ions down a transmembrane gradient through the stator complex provides the energy for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify roles for two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, whereas steric forces comprise the actual "power stroke." Specifically, we propose that ion-induced conformational changes about a proline "hinge" residue in a stator α-helix are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. The proposed model provides a mechanical explanation for several fundamental properties of the flagellar motor, including torque-speed and speed-ion motive force relationships, backstepping, variation in step sizes, and the effects of key mutations in the stator.