Sandbox T1SS T2SS
From Proteopedia
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Description/Function
The Type II secretion system (T2SS) is a secretion pathway found in Gram-negative bacteria. Following transport of a protein from the cytoplasm to the periplasm via the Sec or Tat pathway, the T2SS transports proteins from the periplasm to the extracellular environment[1].
Structure
Each T2SS is made of many general secretory proteins (GSPs). 12-15 GSPs compose one secretory system, and they are often from the same gene cluster and found on the same operon [2]. The T2SS consists of four core components: an outer membrane complex, an inner membrane complex, an ATPase on the cytoplamsic side, and a pseudopilus.
The outer membrane complex consists of the GspD secretin, which uses a beta barrel structure to form a pore through the outer membrane. It is associated with the lipoprotein GspS. The inner membrane complex consists of four proteins: GspC, GspF, GspL, and GspM. Each protein has a different role in secretion, and they all interact with the protein on the periplasmic side. The ATPase is GspE. It has the Walker A motif and uses ATP hydrolysis to power the pseudopilus, which drives protein secretion. The pseudopilus is composed of GspG, GspH, GspI, GspI and GspK. There is evidence that GspG is the sole component of the stalk portion, which uses a ratcheting motion to push proteins through the membrane [2].
Energetics
References
- ↑ Saier, Milton H. “Protein Secretion Systems in Gram-Negative Bacteria.” 2006. Microbe 1: 414-419.
- ↑ 2.0 2.1 Cianciotto, Nicholas. “Type II secretion: a protein secretion system for all seasons.” 2005. Trends in Microbiology 13: 581-588.
