Figure 7.

Cyanobacterial CCRP systems. Schematic models for the in vivo localization of cyanobacterial CCRPs in their respective hosts. Fm7001 forms filament-like strings in Fischerella. In Anabaena, All4981 assembles into pole-arising filament-like structures that traverse through the cell or forms septal-localized bridge-like formations. Syc2039, either independently of other Synechococcus proteins, or in direct cooperation with other putative filamentous proteins, forms long and sometimes helical strings that are often aligned with or in close proximity to the cell periphery. In Synechococcus, HmpF_Syc likely forms a protective proteinaceous layer below the cytoplasmic membrane. In Synechocystis, HmpF_Syn forms crescent-like structures while Slr7083 seemingly underlies the cytoplasmic membrane. Both localization types were also observed for PilB, suggesting a cooperative function.