Functional genome analysis of the uncultivated baterial symbiont of the deep-sea tube worm Riftia pachyptila
Final Report Abstract
During the present project, an in-depth examination of the physiology of the uncultured Riftia pachyptila symbiont was undertaken by means of genomic and proteomic analysis. Details of the sulfide-oxidizing symbiont’s energy generation mechanisms were revealed, which included indications on the potential use of thiosulfate as an alternative energy source besides sulfide. The specifics of the CO2-fixing Calvin cycle were illuminated, which appears to be particularly economical, using a reversible pyrophosphate-dependent phosphofructokinase. Furthermore, the proteomic and genomic results confirmed the idea that nitrate is being used by the symbionts as an alternative electron donor for energy generation, in addition to oxygen. These findings strongly support our reception of the Riftia symbionts as extraordinarily versatile bacteria, which are perfectly adapted to their highly unstable environment at the deep sea vents. Through the comparative analysis of symbionts from two distinct host species, Riftia pachyptila and Tevnia jerichonana, it became furthermore apparent that the tubeworm hosts – even if exposed to distinctly different habitat conditions – are providing their conspecific symbionts with very similar microenvironments inside their bodies. The tubeworms are effectively shielding their endosymbionts from the fluctuations outside and supplying all necessary nutrients in abundance, thus promoting the exceptionally high energy- and biomass production rates of their bacterial partners. The separation and proteomic comparison of individual symbiont morphotypes confirmed the presence of rods and cocci in the examined tissue and indicated that metabolic differences occur between the cells in the respective stages of the symbionts’ life cycle. The exact nature of these metabolic differences needs to be addressed in future studies. Also, the detailed comparative metabolic characterization of symbionts from sulfur-rich and from sulfurdepleted tissue, which is expected to provide valuable information on the symbiont’s strategies to deal with stress and nutrient limitation, will be addressed in the future. Finally, a comparative metaproteomic study lead to new insights into the metabolic interactions between the gutless marine worm Olavius algarvensis and its multiple chemosynthetic bacterial symbionts. Shared metabolic mechanisms of the Olavius γ–symbionts and the Riftia symbiont could be detected.
Publications
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(2011). "Status quo in physiological proteomics of the uncultured Riftia pachyptila endosymbiont." Proteomics 11(15): 3106-3117
Markert, S., A. Gardebrecht, H. Felbeck, S. M. Sievert, J. Klose, D. Becher, D. Albrecht, A. Thürmer, R. Daniel, M. Kleiner, M. Hecker and T. Schweder
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(2012). "Metaproteomics of a gutless marine worm and its symbiotic microbial community reveal unusual pathways for carbon and energy use." Proceedings of the National Academy of Sciences. 109(19):E1173-82
Kleiner, M., C. Wentrup, C. Lott, H. Teeling, S. Wetzel, J. Young, Y.-J. Chang, M. Shah, N. C. VerBerkmoes, J. Zarzycki, G. Fuchs, S. Markert, K. Hempel, B. Voigt, D. Becher, M. Liebeke, M. Lalk, D. Albrecht, M. Hecker, T. Schweder and N. Dubilier
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(2012). "Physiological homogeneity among the endosymbionts of Riftia pachyptila and Tevnia jerichonana revealed by proteogenomics." ISME Journal 6(4): 766-776
Gardebrecht, A., S. Markert, S. M. Sievert, H. Felbeck, A. Thurmer, D. Albrecht, A. Wollherr, J. Kabisch, N. Le Bris, R. Lehmann, R. Daniel, H. Liesegang, M. Hecker and T. Schweder
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(2012). "The Genome of the Obligate Intracellular Parasite Trachipleistophora hominis: New Insights into Microsporidian Genome Dynamics and Reductive Evolution." PLoS Pathog 8(10): e1002979
Heinz, E., T. A. Williams, S. Nakjang, C. J. Noël, D. C. Swan, A. V. Goldberg, S. R. Harris, T. Weinmaier, S. Markert, D. Becher, J. Bernhardt, T. Dagan, C. Hacker, J. M. Lucocq, T. Schweder, T. Rattei, N. Hall, R. P. Hirt and T. M. Embley
