Poster abstracts
Poster number 125 submitted by Mika Schievelbein
The 3' end of MALAT1 forms a partial triple helix in the presence of mascRNA
Mika Schievelbein (Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 45665), Nikhil Vijai (Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556), Jake M. Peterson (Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011), Walter N. Moss (Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011), Jessica A. Brown (Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556)
Abstract:
MALAT1 is a long noncoding RNA whose 3' end is processed via RNase P due to the presence of a tRNA-like structure known as mascRNA. The resulting 3' end of mature MALAT1 terminates in a triple helix formed between a U-rich internal loop and A-rich tract. In the premature transcript, the 3' end of mascRNA engages with a portion of the A-rich tract to form a pre-mascRNA structure that is essential for efficient RNase P cleavage and precludes mature triple helix formation. Yet, the 3'-end structure of the premature MALAT1 is generally unknown. Using UV thermal melts and the MALAT1 triple helix-binding protein METTL16, our results support the formation of a partial triple helix in an RNA containing the regions for the triple helix and pre-mascRNA. Furthermore, our de novo structural model posits that a short stretch of A residues in the A-rich tract engage with U residues in the lower region of the U-rich internal loop. Our preliminary in vitro exonucleolytic degradation assays suggest the partial triple helix is not a stability element in the premature RNA, although METTL16 binding may protect the premature RNA from degradation. Altogether, these findings suggest MALAT1 triple helix formation is a dynamic process and may offer insight into the structural details of MALAT1 maturation.
Keywords: RNA Triple Helix, MALAT1, mascRNA