Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae.[1] Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms of this motility are only partially known.
Twitching motility also allows microorganisms to travel along a surface, but this type of movement is jerky and uses pili as its means of transport. Bacterial gliding is a type of gliding motility that can also use pili for propulsion.
The speed of gliding varies between organisms, and the reversal of direction is seemingly regulated by some sort of internal clock.[2] For example the apicomplexans are able to travel at fast rates between 1–10 μm/s. In contrast Myxococcus xanthus bacteria glide at a rate of 0.08 μm/s.[3][4]
Cell-invasion and gliding motility have TRAP (thrombospondin-related anonymous protein), a surface protein, as a common molecular basis that is both essential for infection and locomotion of the invasive apicomplexan parasite.[5]Micronemes are secretory organelles on the apical surface of the apicomplexans used for gliding motility.
A cell attaches its pili to a surface or object in the direction it is traveling. The proteins in the pili are then broken down to shrink the pili pulling the cell closer to the surface or object that was it was attached to.[6]
b)
Specific motility membrane proteins
Transmembrane proteins are attached to the host surface. This adhesion complex can either be specific to a certain type of surface like a certain cell type or generic for any solid surface. Motor proteins attached to an inner membrane force the movement of the internal cell structures in relation to the transmembrane proteins creating net movement.[7] This is driven by the proton motive force.[8] The proteins involved differ between species. An example of a bacterium that uses this mechanism would be Flavobacterium. This mechanism is still being studied and is not well understood.[9]
c)
Polysaccharide jet
The cell releases a 'jet' of polysaccharide material behind it propelling it forward. This polysaccharide material is left behind.[10]