VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

Such a prodrug-activation mechanism seems to be more widespread innature as we could already identify several other biosynthesis gene clustersin different bacterial genera indicating a highly similar mechanism.[1] Goodrich-Blair, H. (2007): Curr. Opin. Microbiol, 10, 225-230.[2] Herbert, E. E. (2007): Nat. Rev. Microbiol, 5, 634-646.[3] Forst, S. (1997): Annu. Rev. Microbiol, 51, 47-72.[4] Ciche, T. A. (2001): J. Bacteriol, 183, 3117-3126.[5] McInerney, B. V. (1991): J. Nat. Prod, 54, 785-795.[6] Reimer, D. (2009): ChemBioChem, 10, 1997-2001.[7] Park, D. (2009): Mol. Microbiol, 73, 938-949.SIP021Evolution and biogeography of deep-sea bathymodiolinemussel symbiosesK. van der Heijden*, C. Borowski, N. DubilierDepartment of Molecular Ecology - Symbiosis Group, Max Planck Institutefor Marine Microbiology, Bremen, GermanyMytilid mussels of the subfamily Bathymodiolinae host endosymbioticbacteria and are key species in habitats such as hydrothermal vents,hydrocarbon seeps, sunken wood and whale bone falls. Their symbiontsoxidize reduced compounds such as sulfide and methane. The gained energyis used for assimilation of carbon that they transfer to their hosts, thuscontributing significantly to their hosts′ nutrition. Many host species areassociated with sulfur oxidizers, others harbor methane oxidizers, and anumber of species host both functional types co-occurring in a dualsymbiosis.Bathymodiolinae are known from all ocean basins, although most speciesare bound to a specific habitat type depending on their type of symbiontsand adequate substrate availability. It was hypothesized that the subfamilyoriginated in reducing shallow water habitats and immigrated into the deepseahydrothermal vent habitats by using sunken wood, whale falls andhydrocarbon seeps as stepping stones. In order to test this hypothesis, weanalyzed the phylogenies of the hosts and their symbionts and integratedthem with ecological data such as biogeography, habitat type, substrateavailability, depth and types of associated symbionts of a specific hostspecies to test for the presence of correlations. We are examining musselspecies from vents and seeps worldwide. For reconstruction of the hostphylogeny we have analyzed three marker genes, the mitochondrialcytochrome oxidase subunit I (COI) and the NADH-dehydrogenase subunit4 (ND4) genes, and the nuclear 28S rRNA gene. The phylogeny of thebacterial endosymbionts is based on analysis of the 16S rRNA. The resultsof these analyses will give us insight into the evolution of the symbioticinteractions and colonization history of chemosynthetic habitats.SRV001Molecular mechanisms governing the three-componentsystem HbpS-SenS-SenR from Streptomyces reticuliD. Ortiz de Orué Lucana*, M. Roscher, H. SchrempfDepartment of Biology and Chemistry, University of Osnabrück, Osnabrück,GermanyThe novel three-component signalling system HbpS-SenS-SenR from thecellulose degrader Streptomyces reticuli has been shown to sense redoxsignals and to provide this bacterium with an efficient defence systemagainst oxidative stress [1]. The heme-binding and oligomer-forming proteinHbpS is extracellularly located. It interacts with the membrane-embeddedsensor kinase SenS from the two-component system SenS-SenR. Furtheranalyses revealed that the octameric assembly of HbpS is essential for theinteraction with SenS [2]. Furthermore, HbpS has been shown to modulatethe phosphorylation state of the sensor kinase SenS as, in the absence ofoxidative stress conditions, HbpS inhibits SenS autophosphorylationwhereas the presence of heme or iron ions and redox-stressing agentsenhances it [2].Using a number of genetic, biochemical, structure and biophysicalapproaches including site-directed mutagenesis, FRET, CD spectroscopy,fluorescence spectroscopy and immunoblotting, we have demonstrated thatiron-mediated oxidative stress induces both secondary structure and overallintrinsic conformational changes within HbpS. We showed in addition thatHbpS is oxidatively modified, leading to the generation of highly reactivecarbonyl groups and tyrosine-tyrosine bonds [3]. Therefore, it can beproposed that iron-mediated oxidative modifications causing structural andconformational changes in HbpS are responsible for the control of the HbpS-SenS-SenR signalling cascade.[1] Ortiz de Orué Lucana, D. and M.R. Groves (2009): Amino Acids, 37:479-486.[2] Ortiz de Orué Lucana, D. et al (2009): J Mol Biol, 386: 1108-1122.[3] Ortiz de Orué Lucana, D. et al (2010): J Biol Chem, 285: 28086-28096.SRV002Anoxygenic photosynthesis and photooxidative stress: Aparticular challenge for RoseobacterJ. Glaeser* 1 , B. Berghoff 1 , A. Nuss 1 , M. Zobawa 2 , F. Lottspreich 2 , G. Klug 11 Institute for Micro- and Molecular Biology, Justus-Liebig-University,Gießen, Germany2 Protein Analytics, Max-Planck-Insititut für Biochemie, Martinsried,GermanyRoseobacter clade aerobic anoxygenic photosynthetic bacteria are abundantin photic zone environments of marine ecosystems. These bacteria performanoxygenic photosynthesis under oxic conditions, a situation known togenerate singlet oxygen ( 1 O 2) in the closely related anoxygenic phototrophRhodobacter sphaeroides [1]. Compared to Rhb. sphaeroides,photosynthetic membranes of Roseobacter denitrificans generated three foldmore 1 O 2 during light exposure and consequently the key regulator genesrpoE and rpoH II [2, 3] of Rsb. denitrificans were much stronger induced inresponse to 1 O 2 stress compared to Rhb. sphaeroides. The regulon controlledby RpoE was different in R. denitrificans and Rhb. sphaeroides and patternsof synthesized soluble proteins strongly changed upon high light exposure inRsb. denitrificans, but not in Rhb. sphaeroides. Changes in the proteomewere not further promoted by artificial 1 O 2 generation, which indicates thatlight alone generates high levels of 1 O 2 in Rsb. denitrificans. The strongincrease of the small RNA RDs2461 by photooxidative stress [4] implies arole of sRNAs in post-transcriptional regulation of the response to 1 O 2 inRsb. denitrificans. Overall, our data reveal similarities but also significantdifferences in the response of Rsb. denitrificans and Rhb. sphaeroides to1 O 2, most likely a consequence of their different life styles [5].[1] Glaeser J. and Klug G. (2005) Microbiology 151: 1927-1938[2] Anthony, J. R. et al (2005): P Natl Acad Sci USA 102: 6502-6507[3] Nuss A. M. et al (2009): J Bacteriol 191: 220-30[4] Berghoff, B. A. et al (2009): Mol Microbiol 74: 1497-1512[5] Berghoff, B. et al (2011): Environ Microbiol DOI: 10.1111/j.1462-2920.2010.02381.xSRV003The apoptosis inducing factor (AIF)-like mitochondrialoxidoreductase (aifA) mediates reistance towards thePenicillium chryosgenum antifungal protein PAF inAspergillus fumigatusA. Eigentler 1 , B. de Castro Pimentel Figueiredo 2 , T. Magnani Dinamarco 2 ,G.H. Goldman 2 , Gustavo H. Goldman 2 ,F.Marx* 11 Biocenter, Division of Molecular Biology, Innsbruck Medical University,Innsbruck, Austria2 Faculdade de Ciencias Farmaceuticas de Ribeirao Preto, Universidade deSao Paulo, Sao Paulo, BrazilThe antifungal protein PAF from Penicillium chrysogenum is a secretedlow-molecular weight, cysteine-rich and cationic protein that inhibits thegrowth of the zoopathogen Aspergillus fumigatus. Thus PAF represent apromising candidate for the development of novel antimycotic strategies anda detailed characterization of its mode of action is essential.By the use of a genome wide gene expression analysis in A. fumigatus aderegulation of genes involved in oxidative phosphorylation and oxidativestress response after exposure to PAF was determined. Indeed, we observedan increased level of reactive oxygen species (ROS) in PAF-treated hyphae.The determination of the mitochondrial respiration efficiency, the ATPproduction and the copy number of mitochondrial DNA indicated that thederegulation of mitochondrial genes in response to PAF primarily resultedfrom a mitochondrial malfunction but not from a reduction of themitochondrial number. The deletion of the mitochondrial aifA gene resultedin the hypersensitivity of A. fumigatus towards PAF which underlines thefunction of AIFA in the detoxification of PAF-induced ROS. From theseresults we conclude that induction of oxidative stress and mitochondrialmalfunction are central features of PAF toxicity which can finally lead toprogrammed cell death as previously shown [1] .[1] Leiter, É. et al (2005): The antifungal protein PAF severely affects the integrity of the plasmamembrane of Aspergillus nidulans and induces an apoptosis-like phenotype. Antimicrob. AgentsChemother.49: 2445-2453.spektrum | Tagungsband 2011