3G20

Crystal structure of the major pseudopilin from the type 2 secretion system of enterohaemorrhagic Escherichia coli

Summary for 3G20

• Entry DOI: 10.2210/pdb3g20/pdb
• Descriptor: Type II secretion protein, 2-[N-CYCLOHEXYLAMINO]ETHANE SULFONIC ACID, CALCIUM ION, ... (6 entities in total)
• Functional Keywords: general secretory pathway, major pilin, protein transport, complex
• Biological source: Escherichia coli O157:H7
• Total number of polymer chains: 2
• Total formula weight: 28122.19

Authors

Korotkov, K.V.,Gray, M.D.,Kreger, A.,Turley, S.,Sandkvist, M.,Hol, W.G.J. (deposition date: 2009-01-30, release date: 2009-07-28, Last modification date: 2023-09-06)

Primary citation

Korotkov, K.V.,Gray, M.D.,Kreger, A.,Turley, S.,Sandkvist, M.,Hol, W.G.
Calcium is essential for the major pseudopilin in the type 2 secretion system.
J.Biol.Chem., 284:25466-25470, 2009

PubMed Abstract: The pseudopilus is a key feature of the type 2 secretion system (T2SS) and is made up of multiple pseudopilins that are similar in fold to the type 4 pilins. However, pilins have disulfide bridges, whereas the major pseudopilins of T2SS do not. A key question is therefore how the pseudopilins, and in particular, the most abundant major pseudopilin, GspG, obtain sufficient stability to perform their function. Crystal structures of Vibrio cholerae, Vibrio vulnificus, and enterohemorrhagic Escherichia coli (EHEC) GspG were elucidated, and all show a calcium ion bound at the same site. Conservation of the calcium ligands fully supports the suggestion that calcium ion binding by the major pseudopilin is essential for the T2SS. Functional studies of GspG with mutated calcium ion-coordinating ligands were performed to investigate this hypothesis and show that in vivo protease secretion by the T2SS is severely impaired. Taking all evidence together, this allows the conclusion that, in complete contrast to the situation in the type 4 pili system homologs, in the T2SS, the major protein component of the central pseudopilus is dependent on calcium ions for activity.

PubMed: 19640838
DOI: 10.1074/jbc.C109.037655

Experimental method

X-RAY DIFFRACTION (1.78 Å)