Secretion - Secretion in Gram Negative Bacteria

Secretion in Gram Negative Bacteria

Secretion is not unique to eukaryotes alone, it is present in bacteria and archaea as well. ATP binding cassette (ABC) type transporters are common to all the three domains of life. The Sec system constituting the Sec Y-E-G complex (see Type II secretion system (T2SS), below) is another conserved secretion system, homologous to the translocon in the eukaryotic endoplasmic reticulum and the Sec 61 translocon complex of yeast. Some secreted proteins are translocated across the cytoplasmic membrane by the Sec translocon, which requires the presence of an N-terminal signal peptide on the secreted protein. Others are translocated across the cytoplasmic membrane by the twin-arginine translocation pathway (Tat). Gram negative bacteria have two membranes, thus making secretion topologically more complex. There are at least six specialized secretion systems in Gram negative bacteria. Many secreted proteins are particularly important in bacterial pathogenesis.