Poster abstracts
Poster number 79 submitted by Jia Liu
Cofactor Modulation of T box Riboswitch Recognition: Effects of Mg2+ and Spermidine on the T box Antiterminator RNA-tRNA Complex
Jia Liu (Department of Chemistry & Biochemistry, Ohio University), Shu Zhou (Department of Chemistry & Biochemistry, Ohio University), Jennifer V. Hines (Department of Chemistry & Biochemistry, Ohio University)
Abstract:
The T box riboswitch is a gene-expression controlling mechanism in many Gram-positive bacteria. In the T box mechanism, transcription is controlled by the recognition and binding between tRNA and the antiterminator, a secondary structure of the riboswitch formed in the 5ยด-UTR region of the mRNA. Cofactor modulation of tRNA-antiterminator complex formation was investigated using antiterminator model RNA AM. The effects of spermidine and Mg2+ on AM and the AM-tRNA complex were tested by ITC and fluorescence steady-state and anisotropy assays. Both spermidine and Mg2+ facilitated tRNA-AM binding. The optimal combination to facilitate tRNA-AM complex formation was determined to be [Mg2+]=2-5 mM, [spermidine]=2-3 mM, indicating that the combination of the two cofactors might lower the requirement for Mg2+ during in vitro transcription antitermination. Simplified tRNA models were also investigated to determine the extent to which the overall tRNA structure affects acceptor end binding to AM.
Keywords: T box riboswitch, spermidine, antiterminator