TY  - JOUR
A1  - Wencker, Freya D. R
A1  - Marincola, Gabriella
A1  - Schoenfelder, Sonja M. K.
A1  - Maaß, Sandra
A1  - Becher, Dörte
A1  - Ziebuhr, Wilma
T1  - Another layer of complexity in Staphylococcus aureus methionine biosynthesis control: unusual RNase III-driven T-box riboswitch cleavage determines met operon mRNA stability and decay
JF  - Nucleic Acids Research
N2  - In Staphylococcus aureus, de novo methionine biosynthesis is regulated by a unique hierarchical pathway involving stringent-response controlled CodY repression in combination with a T-box riboswitch and RNA decay. The T-box riboswitch residing in the 5′ untranslated region (met leader RNA) of the S. aureus metICFE-mdh operon controls downstream gene transcription upon interaction with uncharged methionyl-tRNA. met leader and metICFE-mdh (m)RNAs undergo RNase-mediated degradation in a process whose molecular details are poorly understood. Here we determined the secondary structure of the met leader RNA and found the element to harbor, beyond other conserved T-box riboswitch structural features, a terminator helix which is target for RNase III endoribonucleolytic cleavage. As the terminator is a thermodynamically highly stable structure, it also forms posttranscriptionally in met leader/ metICFE-mdh read-through transcripts. Cleavage by RNase III releases the met leader from metICFE-mdh mRNA and initiates RNase J-mediated degradation of the mRNA from the 5′-end. Of note, metICFE-mdh mRNA stability varies over the length of the transcript with a longer lifespan towards the 3′-end. The obtained data suggest that coordinated RNA decay represents another checkpoint in a complex regulatory network that adjusts costly methionine biosynthesis to current metabolic requirements.
KW  - allelic replacement
KW  - expression
KW  - translation
KW  - mechanism
KW  - acid
KW  - endoribonuclease
KW  - antitermination
KW  - transcription
KW  - proteins
KW  - geometry
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259029
VL  - 49
IS  - 4
ER  - 
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  -