SCIN is released by Staphylococcus aureus to counteract the host immune defense. The protein binds to and inhibits C3 convertases on the bacterial surface, reducing phagocytosis and blocking downstream effector functions by C3b deposition on its surface []. An 18 residue stretch 31-48 is crucial for SCIN activity [].
One of the virulence mechanisms of Escherichia coli is the production of toxins from dedicated machineries called secretion systems. Seven secretion systems have been described, which assemble from 3 to up-to more than 20 subunits. These secretion systems derive from or have co-evolved with bacterial organelles such as ABC transporters (type I), type IV pili (type 2), flagella (type 3), or conjugative machines (type IV).The type VI secretion system (T6SS) is present in most pathogens that have contact with animals, plants, or humans. T6SS exports Hcp (Haemolysin-Coregulated Protein) and a class of proteins named Vgr (Val-Gly Repeats), whose exact function is still speculative. In addition to Vgr and Hcp proteins, T6SS is characterised by the presence of an AAA+ Clp-like ATPase and of two additional genes icmF and dotU, encoding homologues of T4SS stabilising proteins [].SciN is a lipoprotein tethered to the outer membrane and expressed in the periplasm of E. coli, and is essential for T6SS-dependent secretion of the Hcp-like SciD protein and for biofilm formation [].
SciN (also known as Lip) is a lipoprotein tethered to the outer membrane and expressed in the periplasm of E. coli, and is essential for T6SS-dependent secretion of the Hcp-like SciD protein and for biofilm formation [].