ABSTRACT
In this chapter, the authors review the genetic aspects of the transport systems in microorganisms. Protein for which the signal peptide is synthesized in the cytoplasm are led to the cytoplasmic membrane in prokaryotes or to the ER membrane in eukaryotes and are translocated across the membrane through various secretion mechanisms. The authors review secretion mechanisms other than the Sec proteins and the signal peptidase. Pugsley and his colleagues have been studying the pullulanase secretion mechanisms, and they have proposed an elegant model for pullulanase secretion. The authors also review the fundamental aspects of protein translocation and secretion mechanisms in microorganism, and model examples of extracellular overproduction of the bacterial enzymes have been presented. For extracellular production of secretory proteins by recombinant microbes, good control of the secretion system in the cell is important. Secretory mechanisms other than the Sec proteins may be essential for all secretory proteins to pass through two cell envelopes, especially the outer membrane.
