Sonja-Verena Albers

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Dr. Sonja-Verena Albers
MPI für terrestrische Mikrobiologie
Karl-von-Frisch-Straße
D-35043 Marburg / Germany
Phone: +49 6421 178-426
Email: albers@mpi-marburg.mpg.de

Molecular Biology of Archaea

Flagella

Operons encoding the proteins for flagella assembly have been identified in nearly all so far sequenced archaeal genomes. Interestingly, their subunits resemble proteins of type IV pili assembly systems and not of bacterial flagellar assembly systems. By using deletion mutant analysis we could demonstrate that in Sulfolonbus the flagella are used for motility on plates and attachment to surfaces.

We have recently analysed the flagella assembly system of S. acidocaldarius in more detail. We demonstrated that it uses its flagella for swimming and that they are highly induced upon nitrogen starvation. The deletion of some of the 7 flagella subunits led to the detabilization of other subunits of the flagellar assembly operon. We biochemically characterized FlaI, the ATPase of the flagella operon, and showed that it hexamerizes upon ATP binding. Moreover, ATP hydrolyzing activity was higly stimulated in the presence of S. acidocaldarius lipids. We are currently investigating the assembly and subunit interaction of the S. acidocaldarius flagellum.

Ghosh, A., Albers, S.-V. Assembly of the archaeal flagellum (2011) Biochem Soc Trans,39(1):64-9.
(online access)

Ghosh, A., Hartung, S., van der Does, C., Tainer, J.A., Albers, S.V. Archaeal flagellar ATPase motor shows ATP-dependent hexameric assembly and activity stimulation by specific lipid binding (2011) Biochem J, 437:43-52.
(online access)

Lassak K, Neiner T, Ghosh A, Klingl A, Wirth R, Albers SV. Molecularanalysis of the crenarchaeal flagellum (2012) Mol Microbiol, doi:10.1111/j.1365-2958.2011.07916.x.
(online access)

UV induced pili

We showed that Sulfolobus species express pili upon UV light exposure. Pili formation leads to cell aggregation and we could recently demonstrate, that the cells exchange DNA in these aggregates. Moreover, cell agregation is species specific. We want to study, how strain specific aggregation is established and what determines this specifities. We have indication that the glycosylation of the cell surface protein, the S-layer, has an important role in this process.

Ajon, M., Fröls, S., van Wolferen, M., Stoecker, K., Teichmann, D.,Driessen, A.J.M., Grogan, D.W., Albers, S.V., Schleper, C. (2011) UV-inducible DNA exchange in hyperthermophilic archaea is mediated by type IV pili.Mol Microbiol, 82: 807-817.
(online access)

Biofilm formation in Sulfolobales

It is now well known that microorganisms in nature often live in surface-associated sessile communities referred to as biofilms. Although archaea are frequently detected in biofilm communities of many different environments, biofilm formation process has not yet been studied in much detail within this domain of life. We have recently described and characterized biofilm formation in S. acidocaldarius, S. solfataricus and S. tokodaii. Thus, we have just taken the challenge of elucidating the regulatory mechanisms behind Sulfolobus biofilm formation. with the following perspectives: i) identification and characterization of biofilm-structural components (EPS matrix and cellular surface appendages), ii) identification and characterization of regulatory factors responsible for biofilm development and, iii) revealing the occurrence of cell-cell communication within Sulfolobus biofilm.

So far, we established that all three cell surface appendages, the flagellum, the UV-induced pili and the adhesive pili, play a role in the colonization of surfaces and only the interplay of all three appendages leads to the observed wild type Sulfolobus biofilm phenotype. On other hand, by means of gene expression analysis at the transcriptomic and proteomic levels we were able to describe common biofilm-regulated genes and proteins within different Sulfolobus strains. Interestingly, all the three Sulfolobus strains displayed increased levels of putative transcriptional regulators named as Lrs14-like proteins. Thus, we strongly believe that these homologous transcriptional regulators might constitute a key regulatory factor during Sulfolobus biofilm development.

Koerdt, A., Gödeke, J., Berger, J., Thormann, KM, Albers, S.V. (2010) Crenarchaeal biofilm formation under extreme conditions. PloSONE, 5(11):e14104.

Koerdt, A., Orell, A., Pham, T.K., Mukherjee, J., Wlodkowski, A.,Karunakaran, E., Biggs, C.A., Wright, P.C., Albers, S.V. (2011) Macromolecular Fingerprinting of Sulfolobus Species in Biofilm: A Transcriptomic and ProteomicApproach Combined with Spectroscopic Analysis. J Proteome Res,10:4105-19

Henche, A.L., Koerdt, A., Ghosh, A., Albers, S.V. (2011) Influence of cell surface structures on crenarchaeal biofilm formation using a thermostable green fluorescent protein. Environ Microbiol, doi: 10.1111/j.1462-2920.2011.02638.x.
(online access)