RRM
2007 Rustbelt RNA Meeting
RRM
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Poster abstracts
Abstract:
Many aminoacyl-tRNA synthetase (aaRS) genes and other amino acid related genes in Gram-positive bacteria are regulated by the T box transcription termination mechanism. In this system, the nascent leader RNA transcript senses the charging ratio of the cognate tRNA through specific base pairing interactions. Expression of an individual gene is induced by limitation for its cognate amino acid, which results in reduced charging of the cognate tRNA. Readthrough of a termination site in the leader region of the transcript and expression of the downstream gene relies on stabilization of an antiterminator helix through interactions with the uncharged tRNA, preventing the formation of a terminator helix and allowing synthesis of the full length mRNA.
Specific interactions of the anticodon and the acceptor end of the tRNA with the transcribed leader RNA have been well-characterized by genetic and biochemical methods, supporting the structural transition of the terminator helix and the proposed secondary structure model. However, less is known about the tertiary structure of the leader RNA or the functional role of other conserved RNA elements. Chemical and enzymatic mapping of the 5\' UTR of the Bacillus subtilis glyQS operon (encoding glycyl-tRNA synthetase) has revealed novel tRNA-induced changes at positions near several of these conserved regions within the leader. Mutations of the glyQS leader are discussed, with the C160U mutation shown as a specific example of a conserved nucleotide critical for the formation of the antiterminator helix, and stability of the tRNA:leader RNA complex.
References:
Grundy FJ, Henkin TM. tRNA as a positive regulator of transcription antitermination in B. subtilis. Cell. 1993 Aug 13; 74(3):475-82.
Grundy FJ, Henkin TM. The T box and S box transcription termination control systems. Front Biosci. 2003 Jan 1; 8:d20-31.
Grundy FJ, Henkin TM. Regulation of gene expression by effectors that bind to RNA. Curr Opin Microbiol. 2004 Apr; 7(2):126-31.
Grundy FJ, Moir TR, Haldeman MT, Henkin TM. Sequence requirements for terminators and antiterminators in the T box transcription antitermination system: disparity between conservation and functional requirements. Nucleic Acids Res. 2002b Apr 1; 30(7):1646-55.
Grundy FJ, Winkler WC, Henkin TM. tRNA-mediated transcription antitermination in vitro: codon-anticodon pairing independent of the ribosome. Proc Natl Acad Sci U S A. 2002a Aug 20; 99(17):11121-6.
Merino E, Yanofsky C. Transcription attenuation: a highly conserved regulatory strategy used by bacteria. Trends Genet. 2005 May; 21(5):260-4.
Rollins SM, Grundy FJ, Henkin TM. Analysis of cis-acting sequence and structural elements required for antitermination of the Bacillus subtilis tyrS gene. Mol Microbiol. 1997 Jul; 25(2):411-21.
Yousef MR, Grundy FJ, Henkin TM. Structural transitions induced by the interaction between tRNA(Gly) and the Bacillus subtilis glyQS T box leader RNA. J Mol Biol. 2005 Jun 3; 349(2):273-87.
Keywords: RNA RNA interaction, Structure, Transcription Regulation
