TY  - JOUR
A1  - Müller, Sara
A1  - Windhof, Indra M.
A1  - Maximov, Vladimir
A1  - Jurkowski, Tomasz
A1  - Jeltsch, Albert
A1  - Förstner, Konrad U.
A1  - Sharma, Cynthia M.
A1  - Gräf, Ralph
A1  - Nellen, Wolfgang
T1  - Target recognition, RNA methylation activity and transcriptional regulation of the Dictyostelium discoideum Dnmt2-homologue (DnmA)
JF  - Nucleic Acids Research
N2  - Although the DNA methyltransferase 2 family is highly conserved during evolution and recent reports suggested a dual specificity with stronger activity on transfer RNA (tRNA) than DNA substrates, the biological function is still obscure. We show that the Dictyostelium discoideum Dnmt2-homologue DnmA is an active tRNA methyltransferase that modifies C38 in \(tRNA^{Asp(GUC)}\) in vitro and in vivo. By an ultraviolet-crosslinking and immunoprecipitation approach, we identified further DnmA targets. This revealed specific tRNA fragments bound by the enzyme and identified \(tRNA^{Glu(CUC/UUC)}\) and \(tRNA^{Gly(GCC)}\) as new but weaker substrates for both human Dnmt2 and DnmA in vitro but apparently not in vivo. Dnmt2 enzymes form transient covalent complexes with their substrates. The dynamics of complex formation and complex resolution reflect methylation efficiency in vitro. Quantitative PCR analyses revealed alterations in dnmA expression during development, cell cycle and in response to temperature stress. However, dnmA expression only partially correlated with tRNA methylation in vivo. Strikingly, dnmA expression in the laboratory strain AX2 was significantly lower than in the NC4 parent strain. As expression levels and binding of DnmA to a target in vivo are apparently not necessarily accompanied by methylation, we propose an additional biological function of DnmA apart from methylation.
KW  - DNA methylferase homolog
KW  - drospophila
KW  - TRNA(ASP)
KW  - mechanism
KW  - binding
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123149
SN  - 1362-4962
VL  - 41
IS  - 18
ER  - 
TY  - JOUR
A1  - Meier, Doreen
A1  - Kruse, Janis
A1  - Buttlar, Jann
A1  - Friedrich, Michael
A1  - Zenk, Fides
A1  - Boesler, Benjamin
A1  - Forstner, Konrad U.
A1  - Hammann, Christian
A1  - Nellen, Wolfgang
T1  - Analysis of the Microprocessor in Dictyostelium: The Role of RbdB, a dsRNA Binding Protein
JF  - PLoS Genetics
N2  - We identified the dsRNA binding protein RbdB as an essential component in miRNA processing in Dictyostelium discoideum. RbdB is a nuclear protein that accumulates, together with Dicer B, in nucleolar foci reminiscent of plant dicing bodies. Disruption of rbdB results in loss of miRNAs and accumulation of primary miRNAs. The phenotype can be rescued by ectopic expression of RbdB thus allowing for a detailed analysis of domain function. The lack of cytoplasmic dsRBD proteins involved in miRNA processing, suggests that both processing steps take place in the nucleus thus resembling the plant pathway. However, we also find features e.g. in the domain structure of Dicer which suggest similarities to animals. Reduction of miRNAs in the rbdB- strain and their increase in the Argonaute A knock out allowed the definition of new miRNAs one of which appears to belong to a new non-canonical class.
KW  - microprocessor
KW  - Dictyostelium discoideum
KW  - dsRNA binding protein
KW  - RbdB
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166687
VL  - 12
IS  - 6
ER  -