The major outer membrane lipoprotein and new lipoproteins share a common signal peptidase that exists in the cytoplasmic membrane of Escherichia coli

摘要

>The cell envelope of Escherichia coli possesses several lipoproteins including the major outer membrane lipoprotein. These lipoproteins are synthesized as a signal peptide-carrying precursor that is subsequently modified with glyceride. In this work, lipoprotein signal peptidase that processes the precursor of the major lipoprotein was partially purified from cells harboring a plasmid that carries the gene for this enzyme (1spA). The enzyme was also active against the glyceride-containing precursors of the peptidoglycan-associated lipoprotein and many additional membrane lipoproteins. The unmodified precursor of the major lipoprotein was not attacked by the enzyme. The enzyme was exclusively localized in the cytoplasmic membrane.