Intercellular Diffusion of a Fluorescent Sucrose Analog via the Septal Junctions in a Filamentous Cyanobacterium

• DOI: 10.1128/mbio.02109-14
• Publication Date: 2015-03-18T00:44:20Z
• Authors: Dennis J. Nürnberg; Vicente Mariscal; Jan Bornikoel; Mercedes Nieves-M...; Norbert Krauß; Antonia Herrero; Iris Maldener; Enrique Flores; Conrad W. Mullineaux
• Keywords: Heterocyst; FtsZ

ABSTRACT Many filamentous cyanobacteria produce specialized nitrogen-fixing cells called heterocysts, which are located at semiregular intervals along the filament with about 10 to 20 photosynthetic vegetative in between. Nitrogen fixation these complex multicellular bacteria depends on metabolite exchange between two cell types, heterocysts supplying combined-nitrogen compounds but dependent for photosynthetically produced carbon compounds. Here, we used a fluorescent tracer probe intercellular heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. We show that esculin, sucrose analog, is incorporated by import system into cytoplasm of cells. The cytoplasmic esculin rapidly and reversibly exchanged across vegetative-vegetative vegetative-heterocyst junctions. Our measurements reveal kinetics also metabolic communication lost significant fraction older heterocysts. SepJ, FraC, FraD proteins septa suggested form structures analogous gap Δ sepJ fraC fraD triple mutant shows an altered septum structure thinner denser peptidoglycan layer. Intercellular diffusion fluorescein derivatives impaired this mutant, greatly reduced frequency nanopores septal cross walls. These findings suggest FraD, SepJ important formation junctional constitute major pathway feeding sucrose. IMPORTANCE its relatives exhibit sophisticated prokaryotic multicellularity, differentiated including normal question how communicate metabolites other key understanding bacterial multicellularity. Here provide first information physiologically molecule, analog can be imported system. Once cytoplasm, it among all Photosynthetically likely follows same route from cytoplasm. identify some involved exchange, our results indicate functionally metazoan