SepT, a novel protein specific to multicellular cyanobacteria, influences peptidoglycan growth and septal nanopore formation in Anabaena sp. PCC 7120

作者：Cristina Velázquez-Suárez, Benjamin L. Springstein, Mercedes Nieves‐Morión, Andreas O. Helbig, Ann-Katrin Kieninger, Iris Maldener, Dennis J. Nürnberg, Karina Stucken, Ignacio Luque, Tal Dagan, Antonia Herrero · 发表于：mBio · 年份：2023 · DOI：10.1128/mbio.00983-23 · 被引用次数：7 · 研究领域：Photosynthetic Processes and Mechanisms、Algal biology and biofuel production、Microbial Community Ecology and Physiology

ABSTRACT Anabaena sp. PCC 7120 grows by forming filaments of communicating cells and is considered a paradigm of bacterial multicellularity. Molecular exchanges between contiguous cells in the filament take place through multiprotein channels that traverse the septal peptidoglycan through nanopores connecting their cytoplasms. Besides, the septal-junction complexes contribute to strengthen the filament. In search for proteins with coiled-coil domains that could provide for cytoskeletal functions in Anabaena , we identified SepT (All2460). SepT is characteristic of the phylogenetic clade of filamentous cyanobacteria with the ability to undergo cell differentiation. SepT-GFP fusions indicate that the protein is located at the cell periphery and, conspicuously, in the intercellular septa. During cell division, the protein is found at midcell resembling the position of the divisome. The bacterial adenylate cyclase two-hybrid analysis shows SepT interactions with itself and putative elongasome (MreB, RodA), divisome (FtsW, SepF, ZipN), and septal-junction (SepJ)-related proteins. Thus, SepT appears to rely on the divisome for localization at mature intercellular septa to form part of intercellular protein complexes. Two independently obtained mutants lacking SepT showed alterations in cell size and impaired septal and peripheral peptidoglycan incorporation during cell growth and division. Notably, both mutants showed conspicuous alterations in the array of nanopores present in the...