In Vitro Transcription of E. Coli tRNA Genes Carried by Transducing Phages
Transducing phages have proved very useful in studies involving specific bacterial genes carried by the phage DNA; because of their smaller size, the DNA of these phages is highly enriched in specific bacterial genes as compared with the bacterial chromosome and may be used as template for in vitro RNA transcription. In order to study the transcription of a bacterial tRNA molecule, we have used the transducing phage φ80psup 3 + (1). The su 3 + gene carried by the φ80 phage is the structural gene which specifies a tRNATyr molecule that enables the amber codon, UAG, to be read as tyrosine (2,3). There are two types of tyrosine tRNA’s (I and II) in E.coli, differing by two nucleotides in the variable loop. The main species in E.coli cells is tRNATyr II; the minor species tRNATyr is specified by two identical genes, one of which can undergo a mutation resulting in a single base change in the anticodon region of the tRNA (su 3 + ). The two tRNATyr I genes are located near the φ80 attachment site on the bacterial chromosome and can be transduced by the φ80 bacteriophage as a single or a tandem double copy.
KeywordsSingle Base Change Pancreatic RNase Transduce Phage Vitro Transcription Heavy Strand
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