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The purification and sequence of a temperature-sensitive tryptophan tRNA
The Journal of Biological Chemistry
|June 25, 1979
Summary
A single genetic mutation in Escherichia coli alters transfer RNA tryptophan (tRNATrp), causing temperature sensitivity. This G7 to A7 base change impacts tRNATrp structure and function.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Escherichia coli can exhibit temperature sensitivity due to genetic defects.
- Transfer RNA (tRNATrp) plays a crucial role in protein synthesis.
Purpose of the Study:
- To purify and determine the sequence of temperature-sensitive tRNATrp from Escherichia coli.
- To identify the specific molecular alteration responsible for temperature sensitivity.
Main Methods:
- Purification of tRNATrp using benzoylated DEAE-cellulose chromatography and gel electrophoresis.
- Alternative purification via hybridization to plasmid DNA bound to cellulose.
- Sequence determination using standard molecular biology techniques.
Main Results:
- The temperature-sensitive tRNATrp differs from wild-type by a single nucleotide substitution: Guanine at position 7 (G7) is replaced by Adenine (A7).
- This single base change reduces the base pairing in the CCA stem of the tRNATrp molecule.
Conclusions:
- A specific point mutation (G7A7) in tRNATrp is responsible for the temperature-sensitive phenotype in Escherichia coli.
- The structural consequence of this mutation is a destabilized CCA stem, affecting tRNA function.