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Specific RNA cleavages induced by manganese ions
J Wrzesinski1, D Michałowski, J Ciesiołka
1Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
Abstract:
The specificity and efficiency of manganese ion-induced RNA hydrolysis was studied with several tRNA molecules. In case of yeast tRNA(Phe), the main cleavage occurs at p16 and minor cuts at p17-18, p20-21, p34 and p36-37. The major Mn(II)-induced cut in yeast elongator tRNA(Met) is also located in the D-loop at p16 and it is stronger than that observed in tRNA(Phe). In initiator tRNA(Met) from yeast two strong Mn(II) cleavages of equal intensity occur at p16 and p17. This is in contrast with single, much weaker cuts induced in the D-loop of that tRNA by Mg(II), Eu(III) and Pb(II) ions. Interestingly, in case of yeast tRNA(Glu) the main cleavage caused by Mn(II), Mg(II) and Pb(II) ions occurs in the anticodon loop. The involvement of hypermodified base mnm5s2U in this cleavage was ruled out based on results obtained with in vitro transcript of yeast tRNA(Glu) anticodon arm. Mutation of a single base A37G in the anticodon loop of the transcript drastically reduced the specificity of Mn(II)-induced hydrolysis.
Insights
Manganese ions (Mn(II)) effectively cleave specific sites in transfer RNA (tRNA) molecules, particularly in the D-loop and anticodon loop. This hydrolysis reveals distinct patterns compared to other metal ions, offering insights into tRNA structure and function.
Area of Science:
- Biochemistry
- Molecular Biology
- RNA Structure and Function
Background:
- Transfer RNA (tRNA) molecules are crucial for protein synthesis, with their structure and function influenced by metal ions.
- Metal ions like magnesium (Mg(II)) are essential for tRNA stability and activity, but other ions can also interact with tRNA.
- Understanding metal ion-induced RNA hydrolysis provides insights into RNA structural dynamics and catalytic mechanisms.
Purpose of the Study:
- To investigate the specificity and efficiency of manganese ion (Mn(II))-induced RNA hydrolysis in various yeast tRNA molecules.
- To compare Mn(II)-induced cleavage patterns with those induced by other divalent and trivalent metal ions (Mg(II), Eu(III), Pb(II)).
- To elucidate the role of specific tRNA structural features, such as the anticodon loop and modified bases, in metal ion-mediated hydrolysis.
Main Methods:
- Analysis of RNA hydrolysis patterns induced by manganese ions (Mn(II)) in different yeast tRNA species (tRNA(Phe), tRNA(Met), tRNA(Glu)).
- Comparison of cleavage sites and intensities induced by Mn(II) with those observed using Mg(II), Eu(III), and Pb(II) ions.
- Utilized in vitro transcripts of yeast tRNA(Glu) anticodon arm to investigate the role of specific bases and mutations (A37G) in Mn(II)-induced hydrolysis.
Main Results:
- Mn(II) induced specific cleavage in yeast tRNA(Phe) primarily at p16 in the D-loop, with minor cuts elsewhere.
- Yeast elongator tRNA(Met) showed a strong Mn(II) cleavage at p16, while initiator tRNA(Met) exhibited two strong cleavages at p16 and p17, contrasting with weaker cuts by other ions.
- For yeast tRNA(Glu), Mn(II), Mg(II), and Pb(II) ions predominantly cleaved the anticodon loop, with Mn(II) hydrolysis specificity reduced by an A37G mutation and not involving the mnm5s2U base.
Conclusions:
- Manganese ions exhibit distinct and specific RNA hydrolysis patterns in tRNA molecules, often targeting the D-loop and anticodon loop.
- The cleavage patterns vary significantly depending on the tRNA type and the specific metal ion, highlighting ion-specific interactions with RNA structure.
- The anticodon loop, particularly base A37, plays a crucial role in the specificity of Mn(II)-induced hydrolysis in tRNA(Glu).