VAAM-Jahrestagung 2012 18.–21. März in Tübingen

56that this trapping depends on the actin-like MamK protein. Overall, ourdata suggest that magnetosome segregation and re-localization is tied to anactive, divisome and MamK-dependent mechanism.BDV006The PomX protein is required for cell division in MyxococcusxanthusA. Treuner-Lange*, A. Harms, L. Søgaard-AndersenMPI for terrestrial microbiology, Department of Ecophysiology, Marburg, GermanyFtsZ is a highly conserved component of the bacterial cell divisionmachinery and formation of the FtsZ-ring at the incipient division site isone of the earliest detectable event in the assembly of the divisionmachinery. In bacteria selection of the site of cell division has beenthought to rely on negative regulators only; however, we recently showedthat the ParA-like protein PomZ positively regulates Z-ring formation inMyxococcus xanthus. Briefly, in a pomZ mutant FtsZ-ring formation isstrongly reduced and the FtsZ-rings formed are abnormally positioned.PomZ localization changes with cell cycle progression culminating inlocalization to the incipient division site before and in the absence ofFtsZ.In vitro FtsZ of M. xanthus hydrolyses GTP but do not assemble intofilaments suggesting that GTP hydrolysis-dependent depolymerization isas fast as the GTP-dependent polymerization, thus, precluding filamentaccumulation. PomZ weakly stimulates FtsZ polymerization suggestingthat PomZ functions to directly recruit FtsZ to midcell and to stabilize theZ-ring. Thus, PomZ provides direct positional information for Z-ringformation, thereby, positively regulating positioning of the division site.To identify proteins important for directing PomZ to mid-cell, we focussedon the gene flanking pomZ, i.e. pomX, which encodes a protein with a C-terminal coiled-coil region. A pomX mutant phenocopies a pomZ mutantindicating that PomX is also involved in cell division. Consistently, in theabsence of PomX, FtsZ-ring formation is significantly reduced and the Z-rings formed are abnormally localized. mCherry-PomX localizes in a cellcycle-dependent manner: In short cells, PomX forms a cluster away frommid-cell, and in longer cells a mid-cell cluster. Moreover, in the absence ofPomX, PomZ localization to the off-center cluster and at mid-cell isabolished and in the absence of PomZ, PomX predominantly localizesrandomly and rarely at mid-cell. Additionally, using purified His 6-taggedPomX protein PomZ was pulled out from wild type extracts. Moreover,His 6-PomX forms filaments in a cofactor-independent manner. Accordingto our current working hypothesis PomX and PomZ interact to form acomplex with FtsZ in that way fulfilling two purposes, recruitment of FtsZto mid-cell and stabilization of the Z-ring.BDV007Cell differentiation in biofilms communities of StaphylococcusaureusJ.C. Garcia-Betancur*, A. Yepes Garcia, D. LopezUniversität Würzburg, ZINF, Würzburg, GermanyMicrobial communities embedded in biofilms generally differentiate intodiverse subpopulations of specialized cells [2]. Development of biofilmsrelies on the spatio-temporal distribution of each one of the constituentsubpopulations of specialized cells [3]. The pathogen Staphylococcusaureus is considered an important model to study biofilm development dueto its ability to generate biofilm-mediated chronic infections [1]. Albeit thepresence of specialized cells has been reported in communities of S. aureus[4] it is unknown whether biofilm formation in S. aureus requires thedifferentiation of specialized cell types and if so, what would be thecontribution of those subpopulations to biofilm development.We have developed a new model to study biofilm formation in which S.aureus forms extremely robust biofilms. This is based on the fact thatbiofilm development can be observed when cells grow on agar surfaces. Inthese conditions, the biofilms formed by S. aureus exhibits a sophisticatedarchitecture that correlates with the strains’ ability to form biofilm in vivo.Moreover, transcriptional reporters of genes known to be essential forbiofilm development were created to visualize and monitor theirexpression pattern within the microbial community that conforms thebiofilm. Examination of the expression of these reporters during biofilmformation showed a heterogeneous expression pattern among thecommunity. A subpopulation of cells specialized in producing andsecreting the polysaccharidic extracellular matrix differentiates.Differentiation of this subpopulation is dynamic since the proportion of thespecialized cells varies along the different stages of the development.Similar pattern was observed for the subpopulation of cells responsible forthe synthesis of adhesion proteins. Flow cytometry was used to quantifythe temporal differentiation pattern of these subpopulations involved inbiofilm formation.[1]Otto, M.,(2008) Staphylococcal biofilms.Curr Top Microbiol Immunol 322:207-228[2]Stewart, P.S. & M.J. Franklin,(2008) Physiological heterogeneity in biofilms.Nat Rev Microbiol 6:199-210[3]Vlamakis, H., C. Aguilar, R. Losick & R. Kolter,(2008) Control of cell fate by the formation of anarchitecturally complex bacterial community.Genes Dev 22:945-953[4]Yarwood, J.M., D.J. Bartels, E.M. Volper & E.P. Greenberg,(2004) Quorum sensing in Staphylococcusaureus biofilms.J Bacteriol 186:1838-1850BDV008Eating and being eaten: What bacterial cell biology can tell usabout eukaryogenesisC. Jogler* 1 , F.O. Glöckner 2 , R. Kolter 11 Harvard Medical School, Microbiology and Genetics, Boston, United States2 Max Planck Institute for Marine Microbiology, Bremen, GermanyProkaryotes are defined as a group of organisms generally lacking amembrane-bound nucleus or other membrane-bound organelle; these arethe hallmarks of eukaryotic cells. Yet, species of the bacterial phylumPlanctomycetes have been shown to harbor intra cytoplasmic membranes(ICM). The ICM of the planctomycetal model organism Gemmataobscuriglobus forms two double membranes surrounding the DNA in anucleus-like compartment. In addition, some Planytomycetes divide likeyeasts, via budding. They also lack the characteristic bacterial divisionprotein FtsZ. Furthermore, planctomycetal membrane coat-like proteinsresembling eukaryotic clathrins were recently discovered. Theirinvolvement in vesicle formation and endocytosis-like uptake of proteinshas been demonstrated. Consequently ancestors of modern Planctomycetesmight have contributed to the origin of the eukaryotic cell plan. However,ultimate proof of endocytosis has been hampered by the lack of genetictools for Planctomycetes. To overcome these limitations, we first screenedfor a suitable model organism among planctomycetal species available asaxenic cultures. We identified Planctomyces limnophilus as a potentialcandidate and demonstrated that P. limnophilus displays the characteristicsubcellular compartmentalization of the Planctomycetes. This findingprovided us with the necessary impetus to develop genetic tools for itsmanipulation. Such tools make P. limnophilus relevant as a model forinvestigating the molecular basis of planctomycetal compartmentalizationin general and to unearth the secrets of the planctomycetal impact oneukaryogenesis.BDP001The Streptomyces spore wall synthesizing complex SSSCS. Sigle, E.-M. Kleinschnitz*, W. Wohlleben, G. MuthUniversität Tübingen, Mikrobiologie/Biotechnologie, Tübingen, GermanyThe Mre-proteins of rod-shaped bacteria form a peptidoglycan (PG)synthesizing complex at the lateral wall to ensure elongation growth.Although mycelial Streptomyces coelicolor grows by apical tip extensionwhich does not involve lateral cell wall synthesis, it contains three mreBlikegenes and a complete mreB cluster comprising mreBCD, pbp2 and sfr(rodA). Mutant analysis demonstrated that the mre-genes were not requiredfor vegetative growth but affected sporulation. Mutant spores sufferedfrom a defective spore wall rendering the spores sensitive to highosmolarity, moderate heat and to cell wall damage by lysozyme orvancomycin 1,2 . Study of protein-protein interactions by a bacterial twohybridanalysis revealed a similar interaction pattern as reported for thelateral wall synthesizing complex suggesting that the Streptomyces sporewall is synthesized by a multi-protein complex which resembles the lateralwall synthesizing complex of rod-shaped bacteria 2 . Screening of a genomiclibrary identified several additional interaction partners as novelcomponents of the SSSC. Interaction of MreC, MreD, PBP2 and Sfr withthe eukaryotic type Ser/Thr kinase SCO4078 indicates regulation of theSSSC by protein phosphorylation. Knock out experiments confirmed therole in spore wall synthesis for SCO2097, a small actinomycetes specificmembrane protein, localized within the dcw cluster involved in celldivision and PG synthesis, and SCO2584 which is located next to teichoicacid biosynthetic genes. Since tagF(SCO2997) and SCO2584 mutantsshowed a similar morphological defect as the mre-mutants, teichoic acidsmight also be involved in spore wall synthesis of S. coelicolor.[1] Heichlinger, A., M. Ammelburg, E.- M. Kleinschnitz, A. Latus, I. Maldener, K. Flärdh, W. Wohlleben,and G. Muth. The MreB-like protein Mbl of Streptomyces coelicolor A3(2) depends on MreB for properlocalization and contributes to spore wall synthesis. J Bacteriol,2011,193, 1533-1542[2] Kleinschnitz, E.-M., A. Heichlinger, K. Schirner, J. Winkler, A. Latus, I. Maldener, W. Wohlleben, andG. Muth. Proteins encoded by the mre gene cluster in Streptomyces coelicolor A3(2) cooperate in spore wallsynthesis. Mol Microbiol,2011,79, 1367 - 1379.[3] Kleinschnitz EM, Latus A, Sigle S, Maldener I, Wohlleben W, Muth G. Genetic analysis of SCO2997,encoding a TagF homologue, indicates a role for wall teichoic acids in sporulation of Streptomycescoelicolor A3(2).J Bacteriol, 2011,193:6080-6085.BDP002Magnetosome chains are recruited to cellular division sitesand split by asymmetric septationE. Katzmann* 1,2 , F.D. Müller 1 , C. Lang 3 , M. Messerer 1 , M. Winklhofer 4 ,J. Plitzko 2 , D. Schüler 11 LMU München Biozentrum, Mikrobiologie, Martinsried, Germany2 Max Planck Institut of Biochemistry, Molecular Structural Biology,Martinsried, Germany3 University Stanford, Biology, Stanford CA, United States4 LMU München, Earth and Environmental Sciences, München, GermanyMagnetotactic bacteria navigate along magnetic field lines using wellorderedchains of membrane enclosed magnetic crystals, referred to asmagnetosomes,which have emerged as model to investigate intracellularBIOspektrum | Tagungsband 2012