EnvC, a new lipoprotein of the cytoplasmic membrane of Escherichia coli.

A gene product with an apparent molecular mass of approximately 39,000 Da can be identified in the cytoplasmic membrane of Escherichia coli upon expression of cloned envC. In this communication we report that the product was labelled with [3H]glycerol and [3H]palmitic acid, and a precursor molecule of increased molecular mass was accumulated when cells were treated with globomycin, a specific inhibitor for the prolipoprotein signal peptidase. The same precursor molecule was encoded by an envC mutant gene, in which the cysteine residue in a pentapeptide sequence, Leu-Ile-Ala-Gly-Cys24 within the amino terminal region of EnvC, was replaced by tryptophane (Trp24). This protein was not labelled with [3H]glycerol. The results demonstrate that the envC gene product represents a new lipoprotein of the cytoplasmic membrane of E. coli.