Protein Secretion Systems in Gram-Negative Bacteria

Abstract

Protein export systems are present in all living organisms, including gram-negative bacteria and the eukaryotic organelles that derived from them (Table 1). In contrast to other organisms, however, gram-negative bacteria contain numerous, apparently independent systems for exporting proteins, including at least eight types that mediate export across or insertion into the inner cytoplasmic membrane and another eight that specifically mediate export across or insertion into the outer lipopolysaccharide-containing membrane.