Helical flow of surface protein required for bacterial gliding motility

Abstract

Cells of Flavobacterium johnsoniae and of many other members of the phylum Bacteroidetes exhibit rapid gliding motility over surfaces by a unique mechanism. These cells do not have flagella or pili; instead, they rely on a novel motility apparatus composed of Gld and Spr proteins. SprB, a 669-kDa cell-surface adhesin, is required for efficient gliding. SprB was visualized by electron microscopy as thin 150-nm-long filaments extending from the cell surface. Fluorescence microscopy revealed movement of SprB proteins toward the poles of the cell at ∼2 μm/s. The fluorescent signals appeared to migrate around the pole and continue at the same speed toward the opposite pole along an apparent left-handed helical closed loop. Movement of SprB, and of cells, was rapidly and reversibly blocked by the addition of carbonyl cyanide m-chlorophenylhydrazone, which dissipates the proton gradient across the cytoplasmic membrane. In a gliding cell, some of the SprB protein appeared to attach to the substratum. The cell body moved forward and rotated with respect to this point of attachment. Upon reaching the rear of the cell, the attached SprB often was released from the substratum, and apparently recirculated to the front of the cell along a helical path. The results suggest a model for Flavobacterium gliding, supported by mathematical analysis, in which adhesins such as SprB are propelled along a closed helical loop track, generating rotation and translation of the cell body.cell motility | proton motive force | immunofluorescence microscopy | continuous track | left-handed helix C ells of Flavobacterium johnsoniae, and of many other members of the phylum Bacteroidetes, move rapidly over surfaces at speeds of 1-3 μm/s by gliding motility (1). These cells lack flagella and pili, and the mechanism of cell movement is poorly understood. Flavobacterium gliding is thought to rely on motors embedded in the cell envelope that propel large cell-surface adhesins such as SprB and related proteins (2). Deletion of sprB results in dramatic reduction in motility. Twelve Gld proteins also are required for gliding (3

The Screw-Like Movement of a Gliding Bacterium Is Powered by Spiral Motion of Cell-Surface Adhesins

“…Such cells were tracked in three-dimensional space, which showed that they moved forward by a screw-like mechanism. When viewed in a two-dimensional projection, SprB exhibits periodic motion (11). By attaching a gold nanoparticle to SprB, we were able to track its motion in three-dimensional space.…”

“…Twitching involves the extension and retraction of type IV pili (1-3), but gliding bacteria do not use type IV pili (4)(5)(6)(7). Although the mechanism for gliding is barely understood, we know that Flavobacterium johnsoniae, which exhibits some of the fastest gliding of all known bacteria, has a powerful rotary motor (8) and a mobile cell-surface adhesin, SprB (9)(10)(11). Proteins of the type IX secretion system, which are abundant in gliding bacteria related to Flavobacterium, are required for secretion of SprB to the cell surface (12)(13)(14).…”

Asymmetric distribution of type IV pili triggered by directional light in unicellular cyanobacteria

“…All procedures were done at room temperature (RT). The cell culture was poured into a tunnel assembled by taping a coverslip (36). The coverslip was coated with 0.007% (vol/vol) collodion in isoamyl acetate and air-dried before use.…”

Characterization of the Porphyromonas gingivalis Type IX Secretion Trans-envelope PorKLMNP Core Complex

“…However, none of the T9SS subunits bear the signature of NTPases. By contrast, T9SS-dependent gliding motility has been shown to be dependent on the proton-motive force in F. johnsoniae (36). Energy transducers using the proton-motive force, such as the MotAB, TolQRA, ExbBD-TonB or AglQR complexes (37,38), usually possess negatively charged glutamate or aspartate residues within the hydrophobic TMH.…”