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meoA is the structural gene for outer membrane protein c of Escherichia coli K12
Abstract:
The isolation and characterization of two mutants of Escherichia coli K12 with an altered outer membrane protein c is described. The first mutant, strain CE1151, was isolated as a bacteriophage Me1 resistant strain which contains normal levels of protein c. Mutant cells adsorbed the phage with a strongly decreased rate. Complexes of purified nonheat modified wild type protein c and wild type lipopolysaccharide inactivated phage Me1, indicating that these components are required for receptor activity for phage Me1. When wild type protein c was replaced by protein c of strain CE1151, the receptor-complex was far less active, showing that protein c of strain CE1151 is altered. The second mutant produces a protein c with a decreased electrophoretic mobility, designated as protein c. An altered apparent molecular weight was also observed for one or more fragments obtained after fragmentation of the mutant protein with cyanogen bromide, trypsin and chymotrypsin. Alteration of protein c was not accompanied by a detectable alteration in protein b or its fragments. Both mutations are located at minute 48 of the Escherichia coli K12 linkage map. The results strongly suggest that meoA is the structural gene for protein c.
Insights
Researchers identified two Escherichia coli K12 mutants with altered outer membrane protein c. These changes impact bacteriophage Me1 receptor activity, suggesting meoA is the structural gene for protein c.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Genetics
Background:
- Escherichia coli K12 outer membrane protein c plays a role in bacteriophage Me1 receptor activity.
- Mutations in protein c can affect phage adsorption and receptor complex function.
Purpose of the Study:
- To isolate and characterize Escherichia coli K12 mutants with altered outer membrane protein c.
- To investigate the role of protein c in bacteriophage Me1 resistance and adsorption.
- To identify the genetic locus responsible for protein c alterations.
Main Methods:
- Isolation and characterization of bacteriophage Me1 resistant mutants.
- Analysis of phage adsorption rates in mutant strains.
- Biochemical characterization of wild-type and mutant protein c, including fragmentation analysis.
- Genetic mapping of mutations to the Escherichia coli K12 linkage map.
Main Results:
- Two mutants, CE1151 and a second strain with altered protein c, were identified.
- Mutant protein c from CE1151 significantly reduced receptor-complex activity.
- The second mutant exhibited decreased electrophoretic mobility and altered fragment molecular weights for protein c.
- Both mutations mapped to minute 48 on the Escherichia coli K12 linkage map.
Conclusions:
- Protein c and lipopolysaccharide are essential components for bacteriophage Me1 receptor activity.
- Alterations in protein c significantly impact phage adsorption and receptor function.
- The meoA gene is strongly suggested to be the structural gene for protein c.