IMR Press / FBL / Volume 8 / Issue 4 / DOI: 10.2741/908

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on as a courtesy and upon agreement with Frontiers in Bioscience.

The T box and S box transcription termination control systems
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1 Department of Microbiology, The Ohio State University, 484 W. 12th Avenue, Columbus, OH 43210, USA

Academic Editor: Peter Zuber

Front. Biosci. (Landmark Ed) 2003, 8(4), 20–31;
Published: 1 January 2003
(This article belongs to the Special Issue Prokaryotic transcriptional regulation: beyond the enteric paradigms)

The T box and S box transcription termination control systems are widely used for control of gene expression in Gram-positive bacteria, but are rare in Gram-negative organisms. Both of these systems can be recognized in genomic data because of high conservation of primary sequence and structural elements. The T box system regulates a variety of amino acid-related genes, while the S box system is dedicated to genes involved in methionine metabolism. While both systems involve gene regulation at the level of premature termination of transcription, the molecular mechanisms employed are very different. In the T box system, expression is induced by stabilization of an antiterminator structure in the leader by interaction with the cognate uncharged tRNA; this prevents formation of the competing terminator helix, allowing synthesis of the full-length mRNA. Disruption of conserved leader features results in loss of readthrough. In the S box system, the antiterminator form of the leader is the more stable form. A competing anti-antiterminator must be stabilized by an unknown factor during growth in methionine to prevent formation of the antiterminator, thereby allowing formation of the terminator helix. Disruption of conserved leader elements results in constitutive expression.

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