{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T22:42:08Z","timestamp":1790462528722,"version":"4.1.0"},"reference-count":34,"publisher":"National Academy of Sciences","issue":"26","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2009,6,30]]},"abstract":"<jats:p>\n                    Adhesion pili (fimbriae) play a critical role in initiating the events that lead to intestinal colonization and diarrheal disease by enterotoxigenic\n                    <jats:italic>Escherichia coli<\/jats:italic>\n                    (ETEC), an\n                    <jats:italic>E. coli<\/jats:italic>\n                    pathotype that inflicts an enormous global disease burden. We elucidate atomic structures of an ETEC major pilin subunit, CfaB, from colonization factor antigen I (CFA\/I) fimbriae. These data are used to construct models for 2 morphological forms of CFA\/I fimbriae that are both observed in vivo: the helical filament into which it is typically assembled, and an extended, unwound conformation. Modeling and corroborative mutational data indicate that proline isomerization is involved in the conversion between these helical and extended forms. Our findings affirm the strong structural similarities seen between class 5 fimbriae (from bacteria primarily causing gastrointestinal disease) and class 1 pili (from bacteria that cause urinary, respiratory, and other infections) in the absence of significant primary sequence similarity. They also suggest that morphological and biochemical differences between fimbrial types, regardless of class, provide structural specialization that facilitates survival of each bacterial pathotype in its preferred host microenvironment. Last, we present structural evidence for bacterial use of antigenic variation to evade host immune responses, in that residues occupying the predicted surface-exposed face of CfaB and related class 5 pilins show much higher genetic sequence variability than the remainder of the pilin protein.\n                  <\/jats:p>","DOI":"10.1073\/pnas.0812843106","type":"journal-article","created":{"date-parts":[[2009,6,10]],"date-time":"2009-06-10T21:09:25Z","timestamp":1244668165000},"page":"10793-10798","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":84,"title":["Structure of CFA\/I fimbriae from enterotoxigenic\n                    <i>Escherichia coli<\/i>"],"prefix":"10.1073","volume":"106","author":[{"given":"Yong-Fu","family":"Li","sequence":"first","affiliation":[{"name":"Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4256;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven","family":"Poole","sequence":"additional","affiliation":[{"name":"Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910-7500;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kazuya","family":"Nishio","sequence":"additional","affiliation":[{"name":"Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4256;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ken","family":"Jang","sequence":"additional","affiliation":[{"name":"Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118-2526; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fatima","family":"Rasulova","sequence":"additional","affiliation":[{"name":"Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910-7500;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annette","family":"McVeigh","sequence":"additional","affiliation":[{"name":"Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910-7500;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephen J.","family":"Savarino","sequence":"additional","affiliation":[{"name":"Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910-7500;"},{"name":"Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Di","family":"Xia","sequence":"additional","affiliation":[{"name":"Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4256;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Esther","family":"Bullitt","sequence":"additional","affiliation":[{"name":"Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118-2526; and"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2009,6,30]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.18.3.465-483.2005"},{"key":"e_1_3_3_2_2","first-page":"146","volume-title":"Escherichia coli and Salmonella: Cellular and Molecular Biology","author":"Low D","year":"1996","unstructured":"D Low, et al., Fimbriae. 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