What is the T-box riboswitch leader sequence?

The T-box riboswitch leader is a bacterial RNA regulatory element found upstream of many gene clusters associated with amino acid biosynthesis and tRNA-aminoacylation. T-box riboswitches are capable of sensing tRNA aminoacylation state. When an uncharged tRNA is bound, an antiterminator hairpin is formed; otherwise, a terminator hairpin is formed. Downstream genes are therefore transcribed only in the presence of uncharged tRNA. For more information, see the Rfam entry on T-box riboswitches .

T-box background

T-box riboswitch features

T-box riboswitches have the following structural features. The image below shows the consensus structures of T-box riboswitches within the TBDB. Note that structures can vary from the conserved set.

T-box structural features

T-box riboswitches in synthetic biology

T-box riboswitches can be useful tools in synthetic biology. In accordance with their natural function, they can be used to direct transcription of downstream genes based on tRNA aminoacylation state. More broadly, they can also be used as tRNA-binding elements. For example, Ishida et al. showed that a T-box riboswitch can be fused to an aminoacylating ribozyme to confer specificity to tRNAs recognized by the T-box riboswitch.

Predicting downstream gene function based on T-box riboswitch specificity

Knowing the specificity of a T-box riboswitch regulating a downstream gene may be helpful in predicting that gene's function. For example, amino acid transporters are often difficult to classify, but transporters regulated by T-box riboswitches can be predicted to transport the same amino acid that the T-box riboswitch senses.

T-box riboswitches as antibiotic targets

Since T-box riboswitches are found only in bacteria, they may be attractive antibiotic targets. For example, Frolich et al. demonstrated that small-molecule inhibitors of T-box/tRNA binding can inhibit the growth of Gram-positive bacteria in vitro.

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