Compartmentalization of catalases in Escherichia coli.

Escherichia coli possess three catalase genes: katG codes for protein HPI and katE codes for HPII; katF is also needed for HPII but may be a positive regulatory gene for katE. We have assayed for HPI and HPII in the outer cell membrane, the periplasmic space, the inner membrane, and in the cytoplasm of E. coli. Following synthesis of catalase in the cytoplasm the active katG gene product (HPI) was found in the periplasmic and in the cytoplasmic membrane fractions. HPII remained in the cytoplasm.