Supplementary MaterialsSupplementary Components. that formed polymers PCC 7414 polymerized and formed filaments in several organisms. Additionally, we identified a tetratricopeptide repeat protein – All4981 – in sp. PCC 7120 that polymerized into filaments and viability. Although it did not form filaments PCC 7942 assembled into filaments and a mutant was characterized by an impaired cytokinesis. Mmp13 Our results expand the repertoire of known prokaryotic filament-forming CCRPs and demonstrate that cyanobacterial CCRPs are involved in cell morphology, motility, cytokinesis and colony integrity. and genera are characterized by a round or rod-shaped morphology, respectively, and many strains are motile. Species of the Nostocales order are multicellular and differentiate three types of specialized cells including heterocysts, which fix atmospheric nitrogen under aerobic conditions, hormogonia that are reproductive motile filaments and akinetes, which are dormant cells that are resistant to desiccation. Within the Nostocales, species of the Nostocaceae (e.g., or multiseriate trichomes (more than one filament in a row) as in sp. PCC 7120 (hereafter cells connect and exchange nutrition through intercellular cell-cell cable connections, known as septal junctions, which are believed to comprise the septal junction protein SepJ, FraD5 and FraC,6. SepJ is vital for the multicellular phenotype in and in the coccoid cyanobacterium sp. PCC 6803 (hereafter is certainly tightly controlled with a BYL719 irreversible inhibition up to now undescribed protease12. Aside from its function in cell department, the FtsZ-driven divisome also mediates the localization of SepJ13. MreB functions in a multi-protein complex called the elongasome, where it is a key mediator of longitudinal PG biogenesis that controls the cell shape9,14. In cyanobacteria, MreB plays a role in cell shape determination in sp. PCC 7942 (hereafter deletion strains16,17. In ATCC 29113, the MreBCD operon was shown to be regulated by the hormogonium-specific sigma factor SigJ and is likely involved in the transition of coccoid vegetative cells to the more rod-shaped cells that are characteristic to hormogonia18. Proteins resembling the eukaryotic intermediate filaments (IFs) have been discovered in several bacterial species and were shown to form filaments and and to impact essential cellular processes19. IF proteins exhibit an intrinsic nucleotide-independent polymerization capability that is mediated by the high frequency of coiled-coil-rich regions in their amino acid sequence9,20C22. Eukaryotic IF proteins are generally characterized by a conserved domain name buildup consisting of discontinuous coiled-coil segments that form a central rod domain. This rod domain name is usually N- and C-terminally flanked by globular head and tail domains of variable length22C24. Crescentin is usually a bacterial IF-like CCRP from in a nucleotide-independent manner25. However, so far no Crescentin homologs have been found in other bacteria, indicating that non-spherical or rod-shaped prokaryotic morphologies are putatively controlled by other polymerizing proteins28,29. Apart from Crescentin, many other coiled-coil-rich proteins (CCRPs) with IF-like functions have been identified to polymerize into filamentous structures and to perform cytoskeletal-like functions; however, none of them resembled the eukaryotic IF domain name architecture (reviewed by Lin & Thanbichler (2013)19). Examples are two proteins from whose function has been studied in more detail: FilP and Scy29C31. Gradients of FilP localize at the tip of a growing hyphae and contribute to cellular stiffness29. Scy forms patchy clusters at the sites of novel tip-formation and, together with the scaffolding CCRP DivIVA, orchestrates the polar hyphal growth30. Together with FilP and a cellulose-synthase, these proteins form the polarisome, which manuals peptidoglycan biogenesis and hyphal suggestion development in and and localization assays in morphologically different cyanobacteria. Outcomes Coiled-coil-rich protein are wide-spread in cyanobacteria For the computational prediction of putative filament-forming protein, we surveyed 364 cyanobacterial genomes including 1,225,314 protein-coding sequences (CDSs) for CCRPs. All CDSs in the cyanobacterial genomes where clustered by series similarity into groups of homologous protein (see Strategies). The regularity of CCRPs in each CDS was computed using the COILS algorithm36. The algorithm yielded a summary of 28,737 CDSs with high coiled-coil content material (80 proteins in coiled-coil conformation; Supplementary Document?1). CCRPs had been forecasted in 158,466 proteins households covering all cyanobacterial types. To examine the entire distribution of CCRPs in cyanobacterial genomes, we looked into 1,504 groups of homologous protein including at least three CCRP BYL719 irreversible inhibition people BYL719 irreversible inhibition (Fig.?1). Notably, most proteins households (1,142; 76%).