Cell-Cell Joining Proteins in Heterocyst-forming Cyanobacteria
from: The Cell Biology of Cyanobacteria (Edited by: Enrique Flores and Antonia Herrero). Caister Academic Press, U.K. (2014)
The filamentous, heterocyst-forming cyanobacteria have been studied for decades as prototypes of multicellular prokaryotic organisms. They grow as rows of hundreds of cells and have been described as reproducing by random trichome breakage, implying that the unit of growth is the filament. In the heterocyst-forming cyanobacteria, nitrogen fixation and photosynthesis are spatially separated in different cell types. It is well known that filament growth under diazotrophic conditions depends on the intercellular exchange of substances between the different cell types including regulatory signal molecules and metabolites, but the possible routes through which cells communicate have only recently been subjected to study. At least two different paths could be used for cell-cell communication: the continuous periplasm that is shared by all the cells in the filament and some proteinaceous structures present at the septa between adjacent cells that can mediate, operating as channels, direct intercellular transfer of small water-soluble molecules. This chapter focuses on possible intercellular communication through septal channels and describes the proteins that could compose such channels read more ...