3VOR

Crystal Structure Analysis of the CofA

Summary for 3VOR

• Entry DOI: 10.2210/pdb3vor/pdb
• Descriptor: CFA/III pilin (2 entities in total)
• Functional Keywords: type iv pilin, colonization, cell adhesion
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 18899.98

Authors

Fukakusa, S.,Kawahara, K.,Nakamura, S.,Iwasita, T.,Baba, S.,Nishimura, M.,Kobayashi, Y.,Honda, T.,Iida, T.,Taniguchi, T.,Ohkubo, T. (deposition date: 2012-02-06, release date: 2012-09-26, Last modification date: 2024-10-30)

Primary citation

Fukakusa, S.,Kawahara, K.,Nakamura, S.,Iwashita, T.,Baba, S.,Nishimura, M.,Kobayashi, Y.,Honda, T.,Iida, T.,Taniguchi, T.,Ohkubo, T.
Structure of the CFA/III major pilin subunit CofA from human enterotoxigenic Escherichia coli determined at 0.90 A resolution by sulfur-SAD phasing
Acta Crystallogr.,Sect.D, 68:1418-1429, 2012

PubMed Abstract: CofA, a major pilin subunit of colonization factor antigen III (CFA/III), forms pili that mediate small-intestinal colonization by enterotoxigenic Escherichia coli (ETEC). In this study, the crystal structure of an N-terminally truncated version of CofA was determined by single-wavelength anomalous diffraction (SAD) phasing using five sulfurs in the protein. Given the counterbalance between anomalous signal strength and the undesired X-ray absorption of the solvent, diffraction data were collected at 1.5 Å resolution using synchrotron radiation. These data were sufficient to elucidate the sulfur substructure at 1.38 Å resolution. The low solvent content (29%) of the crystal necessitated that density modification be performed with an additional 0.9 Å resolution data set to reduce the phase error caused by the small sulfur anomalous signal. The CofA structure showed the αβ-fold typical of type IVb pilins and showed high structural homology to that of TcpA for toxin-coregulated pili of Vibrio cholerae, including spatial distribution of key residues critical for pilin self-assembly. A pilus-filament model of CofA was built by computational docking and molecular-dynamics simulation using the previously reported filament model of TcpA as a structural template. This model revealed that the CofA filament surface was highly negatively charged and that a 23-residue-long loop between the α1 and α2 helices filled the gap between the pilin subunits. These characteristics could provide a unique binding epitope for the CFA/III pili of ETEC compared with other type IVb pili.

PubMed: 22993096
DOI: 10.1107/S0907444912034464

Experimental method

X-RAY DIFFRACTION (0.9 Å)