Two DevBCA-like ABC transporters are involved in the multidrug resistance of the cyanobacterium Anabaena sp. PCC 7120.

The filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 is an important model organism for studying cell differentiation, nitrogen fixation, and photosynthesis. This cyanobacterium possesses a high number of membrane transporters. Not much is known about the roles of the membrane transporters, especially the ATP-binding cassette (ABC) transporters, in the multidrug resistance of this cyanobacterium. In the present work, we performed a mutational analysis of the genes alr4280/alr4281/alr4282 and alr3647/alr3648/alr3649 that code for the components of putative ABC exporters and are homologous to the DevBCA heterocyst-specific glycolipid exporter. We show that these genes are essential for resistance to different drugs and are not essential for heterocyst development.