Bacterial extracellular secretion: Transport of α-lytic protease across the outer membrane of Escherichia coli

Abstract

Publisher Summary This chapter discusses four questions, such as to what extent do exoproteins and periplasmic proteins use the same mechanism in crossing the inner membrane? Another issue is whether the exoprotein requires participation of the Sec proteins in the first stages of export. Second question is whether a particular protein traverses the inner and outer membranes in a single step, or in two steps. Have these two mechanisms evolved independently or do they share common protein machinery? The third question is implicit for all proteins using the two-step mechanism: Do these exoproteins fold in the periplasm or in the extracellular milieu? Finally, what are the signals that direct an exoprotein to be exported by the one-step or two-step pathway? The chapter presents the answers obtained using α -lytic protease as a model system, and suggests some areas warranting further investigation.