Type I secretion systems use an ABC transporter

2. Type I secretion systems use an ABC transporter

3. MFP: Membrane Fusion Protein

4. Membrane Fusion Protein (MFP) Proteins travel unfolded signal is usually in the C-terminus of the secreted protein

5. Some known proteins secreted by the type I secretion system The secretion signal is usually located at the C-terminal end of the secreted protein and is not cleaved during secretion. Many secreted proteins have distinctive glycine-rich repeats (GGXGXDXXX) that specifically bind calcium ions. Most, if not all, of the gene products containing these repeats are secreted by the type I pathway. Most secreted proteins contain between a few and more than 50 such repeats. Several studies have shown that these repeats are necessary for the activity of the secreted protein. Some proteins secreted by this pathway do not contain any repeats.

8. Mosaic model of protein secretion via the type II pathway. The Xcp-dependent exoproteins exotoxin A (ETA), containing a Sec-dependent signal peptide (SP), or the phospholipases C (Plc’s), bearing a twin-arginine (RR) signal peptide, are exported across the inner membrane through the Sec and the Tat pathway, respectively. After cleavage of the signal peptides, the exoproteins are recognized in the periplasm by the Xcp system, directed to the secretin XcpQ, and released into the external medium. C = cytoplasm; IM = inner membrane; P = periplasm; OM = outer membrane. Different shades in the Sec and Tat translocons correspond to different subunits.

12. Type IV is not well understood The three subfamilies of type IV secretion (T4S) systems are shown. Conjugation machines deliver DNA to recipient bacteria and other cell types by cell-to-cell contact. DNA-uptake and -release systems exchange DNA with the extracellular milieu independently of contact with target cells. Effector translocators deliver DNA or protein substrates to eukaryotic cells during infection. The effector translocators contribute in markedly different ways to the infection processes of the bacterial pathogens shown. PT, pertussis toxin.

13. In Agrobacterium the T4ss localizes at the cell poles VirB1 that degrades peptidoglycan (muramidase activity) ATPase

14. Type V secretion system: The autotransporters Schematic overview of the type V secretion systems. The four functional domains of the proteins are shown: the signal sequence, the passenger domain, the linker region, and the ß-domain. The autotransporter polyproteins are synthesized and generally exported through the cytoplasmic membrane via the Sec machinery. Interestingly, effector proteins with an unusual extended signal sequence, which purportedly mediates Srp-dependent export, are found in all three categories of type V secretion. Once through the inner membrane, the signal sequence is cleaved and the ß-domain inserts into the outer membrane in a biophysically favored ß-barrel structure that forms a pore in the outer membrane. After formation of the ß-barrel, the passenger domain inserts into the pore and is translocated to the bacterial cell surface, where it may or may not undergo further processing. Also known as two-partner secretion (TPS)

18. glycosylated!! glycosylated!! important for right function of the typeIII secretion system