Markert Stephanie

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Markert
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Stephanie
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  • Preprint
    Physiological proteomics of the uncultured endosymbiont of Riftia pachyptila
    ( 2006-11-14) Markert, Stephanie ; Arndt, Cordelia ; Felbeck, Horst ; Becher, Dorte ; Sievert, Stefan M. ; Hugler, Michael ; Albrecht, Dirk ; Robidart, Julie ; Bench, Shellie ; Feldman, Robert A. ; Hecker, Michael ; Schweder, Thomas
    The bacterial endosymbiont of the deep-sea tube worm Riftia pachyptila has never been successfully cultivated outside its host. In the absence of cultivation data we have taken a proteomic approach based on the metagenome sequence to study the metabolism of this peculiar microorganism in detail. As one result, we found that three major sulfide oxidation proteins constitute ~12% of the total cytosolic proteome, highlighting the essential role of these enzymes for the symbiont’s energy metabolism. Unexpectedly, the symbiont uses the reductive tricarboxylic acid (TCA) cycle in addition to the previously identified Calvin cycle for CO2 fixation.
  • Article
    Genome sequence of the sulfur-oxidizing Bathymodiolus thermophilus gill endosymbiont
    (BioMed Central, 2017-09-02) Ponnudurai, Ruby ; Sayavedra, Lizbeth ; Kleiner, Manuel ; Heiden, Stefan E. ; Thürmer, Andrea ; Felbeck, Horst ; Schlüter, Rabea ; Sievert, Stefan M. ; Daniel, Rolf ; Schweder, Thomas ; Markert, Stephanie
    Bathymodiolus thermophilus, a mytilid mussel inhabiting the deep-sea hydrothermal vents of the East Pacific Rise, lives in symbiosis with chemosynthetic Gammaproteobacteria within its gills. The intracellular symbiont population synthesizes nutrients for the bivalve host using the reduced sulfur compounds emanating from the vents as energy source. As the symbiont is uncultured, comprehensive and detailed insights into its metabolism and its interactions with the host can only be obtained from culture-independent approaches such as genomics and proteomics. In this study, we report the first draft genome sequence of the sulfur-oxidizing symbiont of B. thermophilus, here tentatively named Candidatus Thioglobus thermophilus. The draft genome (3.1 Mb) harbors 3045 protein-coding genes. It revealed pathways for the use of sulfide and thiosulfate as energy sources and encodes the Calvin-Benson-Bassham cycle for CO2 fixation. Enzymes required for the synthesis of the tricarboxylic acid cycle intermediates oxaloacetate and succinate were absent, suggesting that these intermediates may be substituted by metabolites from external sources. We also detected a repertoire of genes associated with cell surface adhesion, bacteriotoxicity and phage immunity, which may perform symbiosis-specific roles in the B. thermophilus symbiosis.
  • Article
    Bacterial symbiont subpopulations have different roles in a deep-sea symbiosis
    (eLife Sciences Publications, 2021-01-06) Hinzke, Tjorven ; Kleiner, Manuel ; Meister, Mareike ; Schlüter, Rabea ; Hentschker, Christian ; Pané-Farré, Jan ; Hildebrandt, Petra ; Felbeck, Horst ; Sievert, Stefan M. ; Bonn, Florian ; Völker, Uwe ; Becher, Dorte ; Schweder, Thomas ; Markert, Stephanie
    The hydrothermal vent tubeworm Riftia pachyptila hosts a single 16S rRNA phylotype of intracellular sulfur-oxidizing symbionts, which vary considerably in cell morphology and exhibit a remarkable degree of physiological diversity and redundancy, even in the same host. To elucidate whether multiple metabolic routes are employed in the same cells or rather in distinct symbiont subpopulations, we enriched symbionts according to cell size by density gradient centrifugation. Metaproteomic analysis, microscopy, and flow cytometry strongly suggest that Riftia symbiont cells of different sizes represent metabolically dissimilar stages of a physiological differentiation process: While small symbionts actively divide and may establish cellular symbiont-host interaction, large symbionts apparently do not divide, but still replicate DNA, leading to DNA endoreduplication. Moreover, in large symbionts, carbon fixation and biomass production seem to be metabolic priorities. We propose that this division of labor between smaller and larger symbionts benefits the productivity of the symbiosis as a whole.
  • Article
    Insight into the evolution of microbial metabolism from the deep-branching bacterium, Thermovibrio ammonificans
    (eLife, 2017-04-24) Giovannelli, Donato ; Sievert, Stefan M. ; Hugler, Michael ; Markert, Stephanie ; Becher, Dorte ; Schweder, Thomas ; Vetriani, Costantino
    Anaerobic thermophiles inhabit relic environments that resemble the early Earth. However, the lineage of these modern organisms co-evolved with our planet. Hence, these organisms carry both ancestral and acquired genes and serve as models to reconstruct early metabolism. Based on comparative genomic and proteomic analyses, we identified two distinct groups of genes in Thermovibrio ammonificans: the first codes for enzymes that do not require oxygen and use substrates of geothermal origin; the second appears to be a more recent acquisition, and may reflect adaptations to cope with the rise of oxygen on Earth. We propose that the ancestor of the Aquificae was originally a hydrogen oxidizing, sulfur reducing bacterium that used a hybrid pathway for CO2 fixation. With the gradual rise of oxygen in the atmosphere, more efficient terminal electron acceptors became available and this lineage acquired genes that increased its metabolic flexibility while retaining ancestral metabolic traits.
  • Preprint
    Transcriptomic and proteomic insight into the mechanism of cyclooctasulfur‐ versus thiosulfate‐oxidation by the chemolithoautotroph Sulfurimonas denitrificans
    ( 2018-10-25) Götz, Florian ; Pjevac, Petra ; Markert, Stephanie ; McNichol, Jesse C. ; Becher, Dorte ; Schweder, Thomas ; Mussmann, Marc ; Sievert, Stefan M.
    Chemoautotrophic bacteria belonging to the genus Sulfurimonas (class Campylobacteria) were previously identified as key players in the turnover of zero‐valence sulfur, a central intermediate in the marine sulfur cycle. S. denitrificans was further shown to be able to oxidize cyclooctasulfur (S8). However, at present the mechanism of activation and metabolism of cyclooctasulfur is not known. Here, we assessed the transcriptome and proteome of S. denitrificans grown with either thiosulfate or S8 as the electron donor. While the overall expression profiles under the two growth conditions were rather similar, distinct differences were observed that could be attributed to the utilization of S8. This included a higher abundance of expressed genes related to surface attachment in the presence of S8, and the differential regulation of the sulfur‐oxidation multienzyme complex (SOX), which in S. denitrificans is encoded in two gene clusters: soxABXY 1Z 1 and soxCDY 2Z 2. While the proteins of both clusters were present with thiosulfate, only proteins of the soxCDY 2Z 2 were detected at significant levels with S8. Based on these findings a model for the oxidation of S8 is proposed. Our results have implications for interpreting metatranscriptomic and ‐proteomic data and for the observed high level of diversification of soxY 2Z 2 among sulfur‐oxidizing Campylobacteria.
  • Article
    Comparative proteomics of related symbiotic mussel species reveals high variability of host-symbiont interactions
    (Springer Nature, 2019-11-04) Ponnudurai, Ruby ; Heiden, Stefan E. ; Sayavedra, Lizbeth ; Hinzke, Tjorven ; Kleiner, Manuel ; Hentschker, Christian ; Felbeck, Horst ; Sievert, Stefan M. ; Schlüter, Rabea ; Becher, Dorte ; Schweder, Thomas ; Markert, Stephanie
    Deep-sea Bathymodiolus mussels and their chemoautotrophic symbionts are well-studied representatives of mutualistic host–microbe associations. However, how host–symbiont interactions vary on the molecular level between related host and symbiont species remains unclear. Therefore, we compared the host and symbiont metaproteomes of Pacific B. thermophilus, hosting a thiotrophic symbiont, and Atlantic B. azoricus, containing two symbionts, a thiotroph and a methanotroph. We identified common strategies of metabolic support between hosts and symbionts, such as the oxidation of sulfide by the host, which provides a thiosulfate reservoir for the thiotrophic symbionts, and a cycling mechanism that could supply the host with symbiont-derived amino acids. However, expression levels of these processes differed substantially between both symbioses. Backed up by genomic comparisons, our results furthermore revealed an exceptionally large repertoire of attachment-related proteins in the B. thermophilus symbiont. These findings imply that host–microbe interactions can be quite variable, even between closely related systems.
  • Article
    Host-microbe interactions in the chemosynthetic Riftia pachyptila symbiosis
    (American Society for Microbiology, 2019-12-17) Hinzke, Tjorven ; Kleiner, Manuel ; Breusing, Corinna ; Felbeck, Horst ; Häsler, Robert ; Sievert, Stefan M. ; Schlüter, Rabea ; Rosenstiel, Philip ; Reusch, Thorsten B. H. ; Schweder, Thomas ; Markert, Stephanie
    The deep-sea tubeworm Riftia pachyptila lacks a digestive system but completely relies on bacterial endosymbionts for nutrition. Although the symbiont has been studied in detail on the molecular level, such analyses were unavailable for the animal host, because sequence information was lacking. To identify host-symbiont interaction mechanisms, we therefore sequenced the Riftia transcriptome, which served as a basis for comparative metaproteomic analyses of symbiont-containing versus symbiont-free tissues, both under energy-rich and energy-limited conditions. Our results suggest that metabolic interactions include nutrient allocation from symbiont to host by symbiont digestion and substrate transfer to the symbiont by abundant host proteins. We furthermore propose that Riftia maintains its symbiont by protecting the bacteria from oxidative damage while also exerting symbiont population control. Eukaryote-like symbiont proteins might facilitate intracellular symbiont persistence. Energy limitation apparently leads to reduced symbiont biomass and increased symbiont digestion. Our study provides unprecedented insights into host-microbe interactions that shape this highly efficient symbiosis.