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Forschungsbericht:

Zellbiologie AG Maier


Maier
Prof. Dr. Uwe Maier




born September 20th 1957

1986 Diploma, Freiburg

1988 Promotion Freiburg

1993 Habilitation, Freiburg

1995 Heisenberg fellow

1995–1997 Associate Professor, Bayreuth

since 1997 Full Professor, Marburg





Research
projects:






Cryptomonads


Cryptomonads, unicellular flagellates, evolved by the enslavement and intracellular reduction of a phototrophic eukaryote within another eukaryote. This evolutionary strategy, secondary endosymbiosis, led to plastids surrounded by three or four membranes. In the case of cryptomonads, the plastid is surrounded by four membranes, but still harbours a remnant cytoplasm of the enslaved alga including a pigmy cell nucleus, the nucleomorph. In an international genome project we have sequenced the nucleomorph genome of one cryptophyte, Guillardia theta. Thereby we detected one of the smallest eukaryotic genomes investigated so far, which is comprised of three little, linear chromosomes. Interestingly the coding capacity of this genome is very small as indicated by the fact that approximately 450 genes were detected. Among these, only 30 encode proteins for plastid functions. At the moment we are investigating several unusual aspects of the nucleomorph and the cell biology of cryptophytes. One of our aims is to elucidate the functions of proteins encoded by nucleomorph-specific ORFs. For this, we have enlarged in our methodological repertoire by using cyanobacteria and Arabidopsis other model organisms. Beside functional aspects, we are interested in the phylogeny of the proteins.

A further focus of our research is the intracellular protein transport in cryptomonads. As the plastid of cryptomonads is surrounded by four membranes and an additional remnant cytoplasm is present, a sophisticated protein transport system evolved within cryptomonads. At the moment we are studying how proteins are transported across the second outermost membrane of the plastid and how they are further distributed.


Diatoms


Similarly to cryptomonads, diatoms evolved in secondary endosymbiosis and harbour a plastid, which is directly surrounded by four membranes. At the moment we are studying one strain, Rhopalodia gibba. This diatom harbours cell inclusions, which are called spheroid bodies. We have shown that these spheroid bodies are intracellular cyanobacteria, which have nitrogen fixation activity. Additionally, we have investigated the phylogeny of the spheroid bodies in more detail and identified a closely related free-living relative. Therefore it is now possible to study genomic and physiological adaptations by changing lifestyle from free-living to intracellular. For this, we have initiated a comparative genome project dealing with the spheroid body genome and that of the free-living relative. First results indeed demonstrate early adaptations in the genomic composition of the spheroid bodies.


Dinoflagellates (together with Dr. Stefan Zauner)


Ceratium horridum is an unusual dinoflagellate. This was shown by its thylakoid organisation and by the localization of little plasmids, the so-called minicircles. These circular molecules are thought to represent the plastid genome of dinoflagellates. In C. horridum the minicirlces are nucleus-encoded as shown by our recent experiments. However, a plastid localization of a minor population of these molecules cannot be ruled out. It was thought that RNA editing acting on transcripts of genes of cyanobacterial origin is restricted to higher plant plastids. In the case of C. horridum we demonstrated for the first time that transcripts originating from minicircle-encoded genes are substitutional edited. We observed an unusual editing pattern, changing in most cases the encoded amino acid or curing stop-codons. At the moment we are involved in the characterization of editing of mitochondrial genes and in the isolation of the mitochondrial genome.

Last, but not least, we are interested in the evolution of chloroplast RNA editing. In order to explain this phenomenon, we have investigated all known editing events and compared cis-acting sequences of editing sites. This approach succeeded in the discovery of the evolution of chloroplast RNA editing.


Publications: (U. Maier group only)


Original papers


Prechtl, J, Kneip, C, Lockhart, P, Wenderoth, K., Maier, UG (2004) Intracellular sphaeroid bodies of Rhopalodia gibba have nitrogen fixing apparatus of cyanobacterial origin. Mol. Biol. Evol. 21: 1477-1481.

Laatsch, T., Zauner, S, Stoebe-Maier, B, Kowallik, K.V, Maier, U.-G. (2004) Plastid-derived single gene minicircles of the dinoflagellate Ceratium horridum are localized in the nucleus. Mol. Biol. Evol. 21: 1318-1322.

Zauner, S., Greilinger, D., Laatsch, T., Kowallik, K, Maier, U.-G. (2004) Substitutional editing of transcripts from genes of cyanobacterial origin in the dinoflagellate Ceratium horridum. FEBS Lett. 577: 535-538.

Hjorth, E., Hadfi, K., Zauner S., Maier, U.-G. (2005) Unique genetic compartmentalization of the SUF system in cryptophytes and characterization of a SufD mutant in Arabidopsis thaliana, FEBS Lett. 579:1129-1135

Kawach, O., Voß, C., Wolff, J., Hadfi K., Maier, U.-G., Zauner S. (2005) Unique tRNA introns of an enslaved algal cell. Mol. Biol. Evol. 22:1694-1701

Gould, S., Sommer, M., Hadfi, K., Zauner, S., Maier, U.-G. (2005) Protein Targeting into the Complex Plastid of Cryptophytes. J. Mol. Evol., in press

Hauth, A.M. Maier, U.G., Lang, B.F., Burger, G. (2005) The Rhodomonas salina mitochondrial genome: Compact gene arrangement and extensive repeat region. Nucl. Acids Res., 33:4433-4442

Sineshchekov, O.A., Govorunova, E.G., Jung, K.H. , Zauner, S., Maier, U.-G., Spudich, J.L. (2005) Rhodopsin-mediated Photoreception in Cryptophyte Flagellates. Biophysical Journal, 89:4310-4319

S. Zauner, C. Klemme, K. Bolte and U.G. Maier (2005) Minicircles, genes of mitochondrial origin and editing of transcripts in a peridinin-containing dinoflagellate. submitted

Kawach, O., Prechtl, J., Nyadwhile, J., Maier, U.G. (2005) Characterization of a cyanobacterial protein involved in coupling a prosthetic group to β-phycocyanin. Under revision

Zauner, S., Stoebe-Maier, B., Gilson P, McFadden, G.I., Lockhart, P, Maier, U.G. (2006) Differential gene transfers and gene duplications in primary and secondary endosymbiosis. Under minor revision

Deschamps P., Haferkamp I., Dauvillée D., Haebel S., Steup M., Buléon A., d’Hulst C., Gould S., Maier U., Neuhaus E., Ball S. (2006) The nature of the periplastidial pathway of amylose synthesis in the cryptophyte Guillardia theta. Euk. Cell, in press

Haferkamp, I., Deschamps, P., Ast, M., Jeblick, W., Maier, U., Ball, S., Ekkehard Neuhaus, H.E. (2006) Molecular and biochemical analysis of periplastidal starch metabolism in the cryptophyte Guillardia theta. Euk. Cell, in press

Tillich M, Lewahrk P., Morton B.M., Maier U.G. (2006) Evolution of Chloroplast RNA Editing. Submitted

Reviews

 
Hjorth, E., Hadfi, K., Gould, S.B., Kawach, O., Sommer, M.S., Zauner, S., Maier, U.-G. (2004) Zero, one, two, three, and perhaps four. Endosymbiosis and the gain and loss of plastids. Endocytobiol. Cell Res. 15: 459-468.

Sommer, M.S., Gould, S.B., Kawach, O., Klemme, C., Voß, C., Zauner, S., Maier U.-G. (2005) Photosynthetic organelles and endosymbiosis. In: Genome Evolution in Eukaryotic Microbes (Laura A. Katz and Debashish Bhattacharya, eds.), accepted

Kawach, O., Sommer, M., Gould, S., Voß, C., Maier, U.-G., Zauner, S. (2005) Nucleomorphs: remnant nuclear genomes. In: Genome Evolution in Eukaryotic Microbes (Laura A. Katz and Debashish Bhattacharya, eds.), accepted

Maier, U (2006) Vom Prokaryoten zum Eukaryoten. Nova Acta Leopoldina, accepted


Diploma Theses


Wolf, Jonci (2004)

Rost, Martina (2004)

Voß, Christine (2004)

Klemme, Cornelia (2004)

Tim Ammon (2005)

Karin Jaschinski (2005)

Janine Büchel (2005)

Katrin Bolte (2005)

Sebastian Zoll (2006)

PhD theses:


Christoph Kneip (2004)

Elmar Hjorth (2005)


Funding


SFB Transregio 1
SFB 395
SFB 593
Graduate School, Intra- and inter-cellular transport and communication


Members of the group


Uwe Maier, head
Stefan Zauner, Assistant Professor

Katrin Bolte, PhD student
Helena Funk, PhD student
Sven Gould, PhD student
Oliver Kawach, PhD student
Cornelia Klemme, PhD student
Peter Poltnigg, PhD student
Maik Sommer, PhD student
Christine Voß, PhD student

Franziska Hempel, Diploma student
Petra Lehmann, Diploma student

Marianne Johannsen, Technician
Christa Zimmermann, Technician

Prof. Dr. E. Mörschel
Dr. K. Wenderoth


Address


Laboratory for Cell Biology
Philipps-Universität Marburg
Karl-von-Firsch-Str.
D-35032 Marburg

Zuletzt aktualisiert: 17.05.2006 · dohle

 
 
 
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