title: A rotary motor drives Flavobacterium gliding.
abstract: Cells of Flavobacterium johnsoniae, a rod-shaped bacterium devoid of pili or flagella, glide over glass at speeds of 2-4 μm/s [1]. Gliding is powered by a protonmotive force [2], but the machinery required for this motion is not known. Usually, cells move along straight paths, but sometimes they exhibit a reciprocal motion, attach near one pole and flip end over end, or rotate. This behavior is similar to that of a Cytophaga species described earlier [3]. Development of genetic tools for F. johnsoniae led to discovery of proteins involved in gliding [4]. These include the surface adhesin SprB that forms filaments about 160 nm long by 6 nm in diameter, which, when labeled with a fluorescent antibody [2] or a latex bead [5], are seen to move longitudinally down the length of a cell, occasionally shifting positions to the right or the left. Evidently, interaction of these filaments with a surface produces gliding. To learn more about the gliding motor, we sheared cells to reduce the number and size of SprB filaments and tethered cells to glass by adding anti-SprB antibody. Cells spun about fixed points, mostly counterclockwise, rotating at speeds of 1 Hz or more. The torques required to sustain such speeds were large, comparable to those generated by the flagellar rotary motor. However, we found that a gliding motor runs at constant speed rather than at constant torque. Now, there are three rotary motors powered by protonmotive force: the bacterial flagellar motor, the Fo ATP synthase, and the gliding motor.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Shrivastava
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Pushkar P
authors.initials: PP
authors.lastname: Lele
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA. Electronic address: hberg@mcb.harvard.edu.
authors.forename: Howard C
authors.initials: HC
authors.lastname: Berg
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D001696:Biomechanical Phenomena; D005417:Flavobacterium / Q000502:physiology*; D008858:Microscopy, Phase-Contrast; D008863:Microspheres; D020409:Molecular Motor Proteins / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D018892:Proton-Motive Force / Q000502:physiology*; D012399:Rotation; D019415:Torque
chemical_list: D018829:Adhesins, Bacterial; D020409:Molecular Motor Proteins