PMID:171254

Citation	James, R (1975) Identification of an outer membrane protein of Escherichia coli, with a role in the coordination of deoxyribonucleic acid replication and cell elongation.J. Bacteriol. 124:918-29
Abstract	Protein G of molecular weight 15,000 is the fourth commonest protein in the outer membrane of Escherichia coli B/r. From experiments described here on the relationship of protein G production to cell elongation and septation, the hypothesis is proposed that protein G is a structural protein of cell elongation. Furthermore, a surplus of protein G is produced when deoxyribonucleic acid synthesis is arrested and septation is thereby prevented. Thus protein G may be an important coordination protein in E. coli for integration of deoxyribonucleic acid synthesis, cell envelope elongation, and septation. Inhibition of normal cell elongation in a rod configuration in E. coli B/r by the novel amidinopenicillanic acid FL1060 was accompanied by changes in the rate of appearance of protein G and several other outer membrane proteins. The rate of appearance of protein G decreased some 70% within 60 min, in parallel with termination of rounds of normal cell elongation. Filament-inducing concentrations of nalidixic acid increased dramatically the rate of appearance of protein G. After 30 min a plateau level some 250% higher than the control value was reached. Similar kinetics were observed in parallel with filament formation induced by incubation of a dnaB mutant of E. coli at the nonpermissive temperature. No change in the rate of appearance of protein G was observed during cephalexin- or benzylpenicillin-induced filament formation, indicating that increased protein G production was not a secondary consequence of filamentation. Cells treated with FL1060 lost their ability to be induced for protein G formation, with nalidixic acid, in parallel with their loss of ability to initiate rounds of normal cell elongation. A pulse-chase experiment demonstrated that the protein G appearing in the outer membrane as a consequence of inhibition of deoxyribonucleic acid synthesis was the result of de novo synthesis rather than of interconversion from previously synthesized protein species. A preliminary characterization of protein G revealed several similarities with the well-characterized lipoprotein of the outer membrane of E. coli. A comparison of the incorporation of several 14C-labeled amino acids into protein G and the lipoprotein revealed substantial differences, however, perhaps ruling out a simple relationship between these two proteins.
Links	PubMed
Keywords	Outer Membrane Protein; Protein G; Cell Wall; Cephalexin; DNA Replication; DNA, Bacterial; Escherichia coli; Molecular Weight; Nalidixic Acid; Penicillanic Acid; Penicillin G; FL1060
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Main Points of the Paper

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• Treatment of the cells to various antibiotics is accompanied by changes to the relative amounts of outer membrane proteins

Materials and Methods Used

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Phenotype Annotations

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Species	Taxon ID	Strain	Gene (if known)	OMP	Phenotype	Details	Evidence	Notes
Escherichia coli B/r				decreased amount of outer membrane protein	Staining Results	Cells treated with FL1060 (Mecillinam)	Staining	Figuere 1
Escherichia coli B/r				increased amount of outer membrane protein	Staining Results	Cells treated with Nalidixic acid	Staining	Figuere 1
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References

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