Accumulation of Alkaliphilic Bacillus Penicillinase Cleaved within the Signal Sequence in Cytoplasm of Escherichia coli

Abstract

Alkaliphilic Bacillus penicillinase produced by Escherichia coli is distributed in several subcellular compartments according to cultivation conditions. The penicillinase that accumulated in particular subcellular fractions of E.coli grown under different conditions was purified and characterized. Periplasmic or extracellular penicillinase (24kDa) was mature protein, indicating that the putative precursor (27kDa) was processed at the correct amino acid residue, probably by signal peptidase I. Cytoplasmic penicillinase contained two unusual proteins(25kDa) that are produced by proteolytic cleavage of the precursor within its signal sequence.