Motility in Filamentous Cyanobacteria
Douglas D. Risser
Abstract
Filamentous cyanobacteria are multicellular organisms that perform oxygenic photosynthesis and frequently exhibit surface motility. This review discusses the underlying mechanism facilitating motility in these organisms, with a focus on recent molecular and genetic studies. While previous explanations for this motility have proposed exotic mechanisms, the current data indicate that all filamentous cyanobacteria produce a similar motility-associated extracellular polysaccharide (EPS) or slime essential for movement and employ a type IV pilus (T4P) motor to power motility. The ( a ) regulation of the motor to facilitate coordinated polarity and phototaxis and ( b ) possible bidirectional feedback between the T4P and motility-associated polysaccharide are discussed as well. Finally, the role of motility in promoting diverse biological phenomena, including dispersal, phototaxis, biofilm formation, granulation, and symbiosis, is explored.