title: Divisome-dependent subcellular localization of cell-cell joining protein SepJ in the filamentous cyanobacterium Anabaena.
abstract: Heterocyst-forming cyanobacteria are multicellular organisms that grow as filaments that can be hundreds of cells long. Septal junction complexes, of which SepJ is a possible component, appear to join the cells in the filament. SepJ is a cytoplasmic membrane protein that contains a long predicted periplasmic section and localizes not only to the cell poles in the intercellular septa but also to a position similar to a Z ring when cell division starts suggesting a relation with the divisome. Here, we created a mutant of Anabaena sp. strain PCC 7120 in which the essential divisome gene ftsZ is expressed from a synthetic NtcA-dependent promoter, whose activity depends on the nitrogen source. In the presence of ammonium, low levels of FtsZ were produced, and the subcellular localization of SepJ, which was investigated by immunofluorescence, was impaired. Possible interactions of SepJ with itself and with divisome proteins FtsZ, FtsQ and FtsW were investigated using the bacterial two-hybrid system. We found SepJ self-interaction and a specific interaction with FtsQ, confirmed by co-purification and involving parts of the SepJ and FtsQ periplasmic sections. Therefore, SepJ can form multimers, and in Anabaena, the divisome has a role beyond cell division, localizing a septal protein essential for multicellularity.
authors: Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Américo Vespucio 49, E-41092, Seville, Spain.
authors: Félix
authors: F
authors: Ramos-León
authors: Vicente
authors: V
authors: Mariscal
authors: José E
authors: JE
authors: Frías
authors: Enrique
authors: E
authors: Flores
authors: Antonia
authors: A
authors: Herrero
mesh_terms: D017033:Anabaena / Q000737:chemistry*; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D008565:Membrane Proteins; C061684:FtsW protein, Bacteria