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A missense mutation in the gene coding for ribosomal protein S17 (rpsQ) leading to ribosomal assembly defectivity in
Abstract:
The conditionally lethal mutation, 2861 mis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and was found to cotransduce at 97% with rpsE (S5). The 2861 mis mutation leads to thermosensitivity and impaired assembly in vivo of 30S ribosomal particles at 42 degrees C. The strain carrying the mutation has an altered S 17 ribosomal protein; the mutational alteration involves a replacement of serine by phenylalanine in protein S 17. Spontaneous reversion to temperature independence can restore the normal assembly in vivo of 30 S ribosomal subunits at 42 degrees C and the normal chromatographical behaviour of the S 17 ribosomal protein in vitro. We conclude therefore that the 2861 mis mutation affects the structural gene for protein S 17 (rpsQ).
Insights
A mutation in Escherichia coli affects ribosomal protein S17, causing temperature sensitivity and impaired 30S ribosomal subunit assembly. This discovery pinpoints the specific gene responsible for these critical cellular functions.
Area of Science:
- Molecular Biology
- Bacteriology
- Genetics
Background:
- Ribosomal proteins are essential for bacterial cell function and viability.
- Mutations affecting ribosomal proteins can lead to thermosensitivity and impaired ribosome assembly.
- The Escherichia coli ribosomal protein gene cluster is a key area for genetic analysis.
Purpose of the Study:
- To map and characterize the conditionally lethal mutation 2861 mis in Escherichia coli.
- To identify the specific ribosomal protein affected by the 2861 mis mutation.
- To elucidate the molecular basis of thermosensitivity and impaired ribosome assembly.
Main Methods:
- Genetic mapping using cotransduction analysis.
- Biochemical characterization of ribosomal protein S17.
- In vivo and in vitro assembly studies of 30S ribosomal subunits.
- Analysis of spontaneous revertants.
Main Results:
- The 2861 mis mutation was mapped to the ribosomal protein gene cluster and cotransduced with rpsE (S5).
- The mutation caused thermosensitivity and defective 30S ribosomal particle assembly at 42°C.
- An altered S17 ribosomal protein was identified, with a serine to phenylalanine substitution.
- Reversion to temperature independence restored normal assembly and S17 protein chromatography.
Conclusions:
- The 2861 mis mutation directly affects the structural gene for ribosomal protein S17 (rpsQ).
- This mutation provides a tool to study the assembly and function of the 30S ribosomal subunit.
- Understanding these mutations is crucial for comprehending bacterial ribosome biogenesis and function.