Bacteria Gliding Motility




Filamentous cyanobacteria Phormidium uncinatum and Anabaena variabilis have nozzle-like pores, 14-16 nm outer diameter and inner hole of about 7nm, near the septa that separate cells of a filament, and glide at rates of up to 10micrometer/sec over wet glass surface and occasionally reverse their direction of gliding.  Polysaccharide secreted through the junctional pores was proposed to propel the multicellular filament.


The rate of propulsion of the slime secretion is about the same as the speed of the gliding movements.  
The slime secretion originates in close proximity to the cross walls. The scale bar represnets 10micrometer.

Averages of side-view (left) and top-view (right) projections of the pore complex of P. uncinatum.

The schematic sketch of the junctional pore organelle in P. uncinatum.

Hoiczyk E, Baumeister W, Current Biology 8, 1161 (1998)


Phylogenetically unrelated bacteria such as M. xanthus and cyanobacteria possess similar nozzle-like organelles.  These structures are believed to function as A motility motors from the observation that the nozzles are widespread among gliding bacteria, involved in slime secretion, appropriately located for propulsion and can generate sufficient force to propel the cells at the observed speeds.


Electron micrograph of a neatively stained isolated cell envelope of M. xanthus.


Electron micrographs of isolated nozzles from M. xanthus. An outer diamter is of ~14nm with an inner hole of ~6nm.



Wolgemuth C, Hoiczyk E, Kaiser D, Oster G, Current Biology 12, 369 (2002)