4G7W

Crystal structure of the N-terminal domain of the minor coat protein pIII from CTXphi

Summary for 4G7W

• Entry DOI: 10.2210/pdb4g7w/pdb
• Related: 4G7X
• Descriptor: Putative uncharacterized protein (2 entities in total)
• Functional Keywords: beta barrel, tola binding domain, selenomethionine-substituted protein, phage coat, protein binding
• Biological source: Vibrio cholerae
• Total number of polymer chains: 3
• Total formula weight: 52883.43

Authors

Kolappan, S.,Ford, C.G.,Craig, L. (deposition date: 2012-07-20, release date: 2012-08-29, Last modification date: 2024-11-20)

Primary citation

Ford, C.G.,Kolappan, S.,Phan, H.T.,Waldor, M.K.,Winther-Larsen, H.C.,Craig, L.
Crystal Structures of a CTX{varphi} pIII Domain Unbound and in Complex with a Vibrio cholerae TolA Domain Reveal Novel Interaction Interfaces.
J.Biol.Chem., 287:36258-36272, 2012

PubMed Abstract: Vibrio cholerae colonize the small intestine where they secrete cholera toxin, an ADP-ribosylating enzyme that is responsible for the voluminous diarrhea characteristic of cholera disease. The genes encoding cholera toxin are located on the genome of the filamentous bacteriophage, CTXϕ, that integrates as a prophage into the V. cholerae chromosome. CTXϕ infection of V. cholerae requires the toxin-coregulated pilus and the periplasmic protein TolA. This infection process parallels that of Escherichia coli infection by the Ff family of filamentous coliphage. Here we demonstrate a direct interaction between the N-terminal domain of the CTXϕ minor coat protein pIII (pIII-N1) and the C-terminal domain of TolA (TolA-C) and present x-ray crystal structures of pIII-N1 alone and in complex with TolA-C. The structures of CTXϕ pIII-N1 and V. cholerae TolA-C are similar to coliphage pIII-N1 and E. coli TolA-C, respectively, yet these proteins bind via a distinct interface that in E. coli TolA corresponds to a colicin binding site. Our data suggest that the TolA binding site on pIII-N1 of CTXϕ is accessible in the native pIII protein. This contrasts with the Ff family phage, where the TolA binding site on pIII is blocked and requires a pilus-induced unfolding event to become exposed. We propose that CTXϕ pIII accesses the periplasmic TolA through retraction of toxin-coregulated pilus, which brings the phage through the outer membrane pilus secretin channel. These data help to explain the process by which CTXϕ converts a harmless marine microbe into a deadly human pathogen.

PubMed: 22942280
DOI: 10.1074/jbc.M112.403386

Experimental method

X-RAY DIFFRACTION (2.9 Å)