Funktionelle Untersuchung der Aminocarboxypropyl-Modifikation in der eukaryotischen18S rRNA
Zusammenfassung der Projektergebnisse
Ribosome biogenesis depends on the concerted action of a large number of nonribosomal proteins and small non-coding RNAs which are necessary for the proper assembly and/or maturation of the ribosomal components. Ribosomal RNA precursors become heavily chemically modified already during transcription as well as during their subsequent processing. These modifications affect rRNA folding, structure and function in an as yet not fully understood manner. In addition to 2-O-methylation and pseudouridylation eleven conserved nucleotides are modified at different atoms of their nucleobases, five in the small ribosomal 18S rRNA and six in the large ribosomal subunit 25S rRNA. These base modifications are catalyzed by sitespecific enzymes. During this project the enzyme responsible for the last step in 18S rRNA U1191 hypermodification, acp-transferase Tsr3, has been identified and characterised. Tsr3 as well as the U hypermodification are conserved in all eukaryotes. Tsr3 localizes in the cytoplasm and acp-transfer is important for the final processing of the 20S rRNA precursor to 18S rRNA. Furthermore all methyltransferases responsible for 25S rRNA base modifications were identified in the cause of the project. Whereas methyltransferases Bam2, Bam5 and Bam6 were fungal specific, methyltransferases Rrp8, Rcm1 and Nop2 were conserved in all eukaryots. An increasing number of rRNA base modifying enzymes turns out to be involved in severe human developmental diseases and cellular disorders. This includes methyltransferase Nep1, a point mutation of which causes the Bowen-Conradi syndrome, the human Nop2 homologue NSUN1 (p120) which has been known for long as a tumour marker and recently Rcm1, which turned out to be important for organismal life span. All human homologues of the yeast methyltransferases mentioned above were functionally expressed in yeast. This provides excellent model systems to study the biochemical and cellular disturbances caused by the malfunctions of the respective human methyltransferases.
Projektbezogene Publikationen (Auswahl)
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(2012/13) Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in Saccharomyces cerevisiae. Nucl. Acids Res. 41: 1151-1163
Sharma, S., Watzinger, P., Kötter, P. and Entian, K.-D.
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(2013) Yeast Rrp8p, a novel methyltransferase responsible for m1A 645 base modification of 25S rRNA. Nucl. Acids Res.41. 1151-1163
Peifer, C., Sharma; S., Watzinger; P., Lamberth; S., Kötter; P. und Entian, K.-D.
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(2013). Yeast Nop2 and Rcm1 methylate C2870 and C2278 of the 25S rRNA, respectively. Nucl. Acids Res. 41: 9062- 9076
Sharma, S., Yang, J., Watzinger, P. Kötter, P. and Entian, K.-D.
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(2013/4) Identification of novel methyltransferases, Bmt5 and Bmt6, responsible for the m3U methylations of 25S rRNA in Saccharomyces cerevisiae. Nucl. Acids Res. (2014) 42: 3246- 3260
Sharma, S., Yang, J., Düttmann, S., Watzinger, P., Kötter, P. and Entian K.-D.
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(2015) Methylation of ribosomal RNA by NSUN5 is a conserved mechanism modulating organismal life span. Nature Commun.6: 6158
Schosserer, M., Minois, N., Angerer, T.B., Amring, M., Dellago, H., Harreither, E., Calle-Perez, A., Pircher, A., Gerstl, M.P., Pfeifenberger, S., Brandl, C., Sonntagbauer, M., Kriegner, A., Linder, A., Weinhäusel, A., Mohr, T., Steiger, M., Mattanovich, D., Rinnerthaler, M., Karl, T., Sharma, S., Entian, K.-D., Kos, M., Breitenbach, M., Wilson, I.B.H., Polacek, N., Grillari- Voglauer, R., Breitenbach-Koller, and L., Grillari, J.
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(2016) Ribosome biogenesis factor Tsr3 is the aminocarboxypropyl transferase responsible for 18S rRNA hypermodification in yeast and humans Nucl. Acids Res. 44, 4304–4316
Britta Meyer, Jan Philip Wurm, Sunny Sharma, Carina Immer, Denys Pogoryelov, Peter Kötter, Denis L. J. Lafontaine, Jens Wöhnert, and Karl-Dieter Entian
