Specific Biosynthesis of an Envelope Protein of Escherichia coli

Abstract

A UNIQUE structural protein in the envelope of Escherichia coli, of molecular weight about 7,500 and covalently attached to the peptidoglycan, was found by Braun et al.^1–4, who reported that its amino-acid sequence lacks histidine, proline, glycine, cysteine, phenylalanine and tryptophan⁴. Recently we found that this lipoprotein exists in the E. coli envelope fraction not only in the bound form found by Braun et al.^1–3 but also in a free form, not covalently attached to the peptidoglycan⁵. This form accounts for about two-thirds of the lipoprotein and serves as a precursor of the bound form⁵. We describe here an in vivo situation in which only this lipoprotein is biosynthesized. Using these conditions, we have investigated the biosynthetic mechanism of this envelope protein.