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

67CEP009The cation diffusion facilitator proteins MamB and MamM ofMagnetospirillum gryphiswaldense are involved in magnetitebiomineralization and magnetosome membrane assemblyR. Uebe* 1 , K. Junge 1 , V. Henn 1 , G. Poxleitner 1 , E. Katzmann 1,2 , J. Plitzko 2 ,R. Zarivach 3 , T. Kasama 4 , G. Wanner 1 , M. Pósfai 5 , L. Böttger 6 ,B. Matzanke 6 , D. Schüler 11 Bereich Mikrobiologie/Ludwig-Maximilians-Universität, DepartmentBiologie I, München, Germany2 Max Planck Institut für Biochemie, Martinsried, Germany3 Ben Gurion University of the Negev, Beer-Sheva, Israel4 Technical University of Denmark, Kongens Lyngby, Denmark5 University of Pannonia, Veszprém, Hungary6 Universität zu Lübeck, Lübeck, GermanyMagnetotactic bacteria have the ability to orient along geomagnetic fieldlines based on the formation of intracellular nanometer-sized, membraneenclosedmagnetic iron minerals, called magnetosomes. The formation ofthese unique bacterial organelles involves several processes such ascytoplasmic membrane invagination and magnetosome vesicle formation,accumulation of large amounts of iron in the vesicles and crystallization ofmagnetite. Among the most abundant proteins associated with themagnetosome membrane of Magnetospirillum gryphiswaldense are MamBand MamM, which were implicated in magnetosomal iron transportbecause of their similarity to the cation diffusion facilitator family. Herewe demonstrate that MamB and MamM are multifunctional proteinsinvolved in several steps of magnetosome formation. Whereas bothproteins are essential for magnetite biomineralization, only deletion ofmamB resulted in loss of magnetosome membrane vesicles. MamBstability depended on the presence of MamM by formation of aheterodimer complex. In addition, MamB was found to interact withseveral other proteins including the PDZ1 domain of MamE, a putativemagnetosome associated protease. Whereas any modification of MamBresulted in loss of function, substitution of amino acids within MamM leadto increased formation of polycrystalline instead of single crystals formedin the wild type. A single amino acid substitution within MamM resultedin the formation of crystals consisting of the iron(III) oxide hematite,which coexisted with crystals of the mixed-valence oxide magnetite.Together, the data indicate that MamM and MamB have complexfunctions and are involved in the control of different key steps ofmagnetosome formation, which are linked by their direct interaction.CEP010Energy conservation in Archaea: the unique way of IgnicoccusS. Daxer* 1 , L. Kreuter 1 , U. Küper 1 , R. Rachel 2 , H. Huber 11 Universität Regensburg, Institut für Mikrobiologie, Regensburg, Germany2 Universität Regensburg, Zentrum für Elektronenmikroskopie der Fakultätfür Biologie und Vorklinische MedizinI, Regensburg, GermanyIn prokaryotes, only cytoplasmic membranes have been described so far toharbor ATP synthase complexes. The hyperthermophilic,chemolithoautotrophic Crenarchaeon Ignicoccus hospitalis (1) is the firstorganism, which does not follow this rule. The organism exhibits anunusual cell envelope consisting of an inner and an outermost membranethat are separated by a huge inter-membrane compartment (IMC).Recently it has been shown that the ATP synthase and H 2:sulfuroxidoreductase complexes of I. hospitalis are located in the outermostmembrane (2). As a consequence this membrane is energized by harboringthe primary and secondary proton pumps which are necessary for energyconservation within the IMC. As a further characteristic the outermostmembrane contains multiple copies of the pore-forming complex Ihomp1,which was proposed to be a prerequisite for the attachment and interactionwith Nanoarchaeum equitans. Since I. hospitalis is the only known hostfor this organism (3) the localization of all these complexes wasinvestigated in all members of the genus Ignicoccus. Immunofluorescenceexperiments with whole cells showed that the extraordinary localization ofthe ATP synthase and H 2:sulfur oxidoreductase complex is a commonfeature of all known members of the genus Ignicoccus. Therefore, theoutermost membrane of all Ignicoccus strains is energized and ATP isgenerated in the IMC. Further investigations showed that the acetyl-CoAsynthetasewhich activates acetate to acetyl-CoA by consuming ATP isalso associated to the outermost membrane of all Ignicoccus members. Incontrast, the pore-forming complex Ihomp1 is exclusively found on thecell surface of I. hospitalis, supporting the hypothesis of its involvement inthe attachment of N. equitans.(1) Paper W. et al. 2007 Int. J. Syst. Evol. Microbiol. 57: 803-808(2) Kueper U. et al. 2010 PNAS 107: 3152-3156(3) Jahn U. et al. 2008 J. Bacteriol. 190: 1743-1750(4) This project is supported by a grant from the DFGCEP011Adsorption kinetics of cell wall components of gram positivebacteria on technical surfaces studied by QCM-DM. Suhr* 1 , T. Günther 1 , J. Raff 2,3 , K. Pollmann 31 Helmholtz-Center Dresden-Rossendorf, Institute of Radiochemistry,Biophysics, Dresden, Germany2 Helmholtz-Center Dresden-Rossendorf, Institute of Radiochemistry,Biogeochemistry, Dresden, Germany3 Helmholtz-Center Dresden-Rossendorf, Helmholtz Institute Freiberg forResource Technology, Dresden, GermanyIn general, the cell wall components of gram-positive bacteria e.g. singlelipid bilayer, peptidoglycan, Surface-layer proteins (S-layer) and otherbiopolymers are well studied. These cell wall components are interestingfor several bio-induced technical applications such as biosorptivematerials. Although biosorption processes have been intensivelyinvestigated, the investigation of metal interaction with biomolecules aswell as adsorption processes on substrates on molecular level remainschallenging.In our work we used the quartz crystal microbalance with dissipationmonitoring (QCM-D) in order to study the layer formation of cell wallcompounds and interaction processes on the nano scale range.This analytical method allows the detailed detection of array formation ofbacterial S-layer proteins and gives a better understanding of the selfassemblingprocesses. S-layer proteins as a part of the outer cell envelopeof many eubacteria and archaea form paracrystalline protein lattices instrain depended geometrical structures [1]. Once isolated the proteinsexhibit the ability to form these lattices on different kinds of interfaces andpossesses equal to the bacteria cells high metal binding capacities. Theseproperties open a wide spectrum of applications e.g. ultrafiltrationmembranes for organic and inorganic ions and molecules, templates for thesynthesis of catalytic nanoparticles and other bio-engineered materials [2, 3].By performing different experiments with and without modification oftechnical surfaces with adhesive promoters e.g. polyelectrolytes it ispossible to make exact statements regarding coating kinetics, layerstability and interaction with metals. Subsequent atomic force microscopy(AFM) studies enable the imaging of bio nanostructures and revealcomplex information of structural properties. Aim of these investigationsis the assembly of a simplified biological multilayer based on cellcompounds of gram positive bacteria in order to clarify sorption processesin a complex system. The understanding of coating, biological andbiological-metal interaction processes is interesting for different technicalapplications.[1] U.B. Sleytr et al., Prog. Surf. Sci. 68 (2001), 231-278.[2] K. Pollmann et al., Biotechnology Advances 24 (2006), 58- 68.[3] J. Raff et al., Chem. Mater. 15 (2003), 240-244.CEP012Visualization of an S-layer in the anammox bacteriumKuenenia stuttgartiensisM. van Teeseling* 1 , A. Klingl 2,3 , R. Rachel 2 , M. Jetten 1 , L. van Niftrik 11 Radboud University Nijmegen, Microbiology, Nijmegen, Netherlands2 Universitaet Regensburg, Centre for EM, Regensburg, Germany3 Philipps Universität Marburg, LOEWE Research Centre for SyntheticMicrobiology (SYNMIKRO), Marburg, Germany“Candidatus Kuenenia stuttgartiensis” is an anaerobic ammoniumoxidizing (anammox) bacterium belonging to the order of Brocadiales inthe phylum of the Planctomycetes. Anammox bacteria are important innature where they contribute significantly to oceanic nitrogen loss and areapplied in wastewater treatment for the removal of ammonium. The cellbiology of anammox bacteria is extraordinary; the cells are divided intothree membrane-bounded compartments. In addition, the cell wall of K.stuttgartiensis does not classify as a typical bacterial cell wall, since itlacks peptidoglycan and does not seem to have a typical outer membrane.The question thus arises how the structural integrity of the cells ismaintained. To answer this question the cell wall was studied via freezeetching experiments. Electron micrographs showed the presence of ahexagonal surface layer (S-layer) in the majority of K. stuttgartiensis cells.S-layers, crystalline two-dimensional arrays of proteinaceous subunits thatmake up the outermost layer of many bacterial cell envelopes, have beenpreviously found to have a shape determining function in some bacteria. Itis therefore hypothesized that the S-layer could provide structural integrityto the K. stuttgartiensis cell. Currently attempts are being made to isolatethe S-layer fromK. stuttgartiensiscells to characterize the S-layer andidentify the protein (subunits).BIOspektrum | Tagungsband 2012