supf

supF is a gene encoding a suppressor tRNA used as a mutational reporter in bacterial mutagenesis assays. It is most widely employed in supF mutagenesis systems based on M13-derived vectors that carry the supF locus alongside a test sequence. In these assays, the ability of the supF tRNA to read through amber (stop) codons in a reporter context permits functional expression, and mutations that alter suppression change the phenotype used to score mutations.

Mechanistically, the supF tRNA recognizes the amber stop codon and inserts an amino acid, allowing translation to continue. When the supF gene or its suppression function is perturbed by mutations, the efficiency of suppression changes, yielding a measurable difference in selectable phenotypes such as phage plaque counts or colony formation. The resulting data provide a readout of mutation frequency in the input DNA sample and can be used to characterize mutagenic effects.

Origin and use: The supF system emerged as a convenient in vitro mutagenesis and mutagenicity assay. It is widely used in genetic toxicology, studies of DNA repair and replication fidelity, and mutational spectrum analysis. It complements other reporter systems and is often used with vectors such as pSP189 or related M13/phagemid platforms.

Limitations: Performance depends on host strain background, vector design, and experimental conditions. Endogenous suppressor activity and selection biases can influence results, so appropriate controls are essential for interpretation.