{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T22:14:45Z","timestamp":1788300885435,"version":"build-2803163510"},"reference-count":44,"publisher":"American Chemical Society (ACS)","issue":"4","license":[{"start":{"date-parts":[[2015,1,4]],"date-time":"2015-01-04T00:00:00Z","timestamp":1420329600000},"content-version":"vor","delay-in-days":366,"URL":"https:\/\/pubs.acs.org\/page\/policy\/authorchoice_termsofuse.html"}],"funder":[{"DOI":"10.13039\/100000057","name":"National Institute of General Medical Sciences","doi-asserted-by":"publisher","award":["8P20GM103420-10"],"award-info":[{"award-number":["8P20GM103420-10"]}],"id":[{"id":"10.13039\/100000057","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000097","name":"National Center for Research Resources","doi-asserted-by":"publisher","award":["5P20RR017708-10"],"award-info":[{"award-number":["5P20RR017708-10"]}],"id":[{"id":"10.13039\/100000097","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,2,4]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The anthrax protective antigen (PA) is an 83 kDa protein that is one of three protein components of the anthrax toxin, an AB toxin secreted by Bacillus anthracis. PA is capable of undergoing several structural changes, including oligomerization to either a heptameric or octameric structure called the prepore, and at acidic pH a major conformational change to form a membrane-spanning pore. To follow these structural changes at a residue-specific level, we have conducted initial studies in which we have biosynthetically incorporated 5-fluorotryptophan (5-FTrp) into PA, and we have studied the influence of 5-FTrp labeling on the structural stability of PA and on binding to the host receptor capillary morphogenesis protein 2 (CMG2) using 19F nuclear magnetic resonance (NMR). There are seven tryptophans in PA, but of the four domains in PA, only two contain tryptophans: domain 1 (Trp65, -90, -136, -206, and -226) and domain 2 (Trp346 and -477). Trp346 is of particular interest because of its proximity to the CMG2 binding interface, and because it forms part of the membrane-spanning pore. We show that the 19F resonance of Trp346 is sensitive to changes in pH, consistent with crystallographic studies, and that receptor binding significantly stabilizes Trp346 to both pH and temperature. In addition, we provide evidence that suggests that resonances from tryptophans distant from the binding interface are also stabilized by the receptor. Our studies highlight the positive impact of receptor binding on protein stability and the use of 19F NMR in gaining insight into structural changes in a high-molecular weight protein.<\/jats:p>","DOI":"10.1021\/bi401405s","type":"journal-article","created":{"date-parts":[[2014,1,3]],"date-time":"2014-01-03T14:18:00Z","timestamp":1388758680000},"page":"690-701","source":"Crossref","is-referenced-by-count":17,"title":["19F Nuclear Magnetic Resonance and Crystallographic\nStudies of 5-Fluorotryptophan-Labeled\nAnthrax Protective Antigen and Effects of the Receptor on Stability"],"prefix":"10.1021","volume":"53","author":[{"given":"Fatemeh","family":"Chadegani","sequence":"first","affiliation":[{"name":"Wichita State University , , , ,","place":["Wichita, Kansas, United States, 67260"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Scott","family":"Lovell","sequence":"additional","affiliation":[{"name":"University of Kansas , , , ,","place":["Lawrence, Kansas, United States, 66047"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vennela","family":"Mullangi","sequence":"additional","affiliation":[{"name":"Case Western Reserve University , , , ,","place":["Cleveland, Ohio, United States, 44106"]},{"name":"Cleveland State University , , , ,","place":["Cleveland, Ohio, United States, 44115"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masaru","family":"Miyagi","sequence":"additional","affiliation":[{"name":"Case Western Reserve University , , , ,","place":["Cleveland, Ohio, United States, 44106"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kevin P.","family":"Battaile","sequence":"additional","affiliation":[{"name":"Hauptman-Woodward Medical Research Institute , , , ,","place":["Argonne, Illinois, United States, 60439"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James G.","family":"Bann","sequence":"additional","affiliation":[{"name":"Wichita State University , , , ,","place":["Wichita, Kansas, United States, 67260"]},{"name":"The University of Kansas School of Medicine\u2212Wichita , , ,","place":["Wichita, Kansas, United States, 67214-3199"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2014,1,3]]},"reference":[{"key":"2026090117324707200_cit1","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1038\/n35101999","article-title":"Identification\nof the cellular receptor for anthrax toxin","volume":"414","author":"Bradley","year":"2001","journal-title":"Nature"},{"key":"2026090117324707200_cit2","doi-asserted-by":"crossref","first-page":"5170","DOI":"10.1073\/pnas.0431098100","article-title":"Human capillary\nmorphogenesis protein 2 functions as an anthrax toxin receptor","volume":"100","author":"Scobie","year":"2003","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit3","doi-asserted-by":"crossref","first-page":"15583","DOI":"10.1073\/pnas.1010145107","article-title":"Heterodimeric integrin complexes\ncontaining \u03b21-integrin promote internalization and lethality\nof anthrax toxin","volume":"107","author":"Martchenko","year":"2010","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit4","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1046\/j.1462-5822.2000.00052.x","article-title":"Proteolytic\nactivation of receptor-bound\nanthrax protective antigen on macrophages promotes its internalization","volume":"2","author":"Beauregard","year":"2000","journal-title":"Cell. Microbiol."},{"key":"2026090117324707200_cit5","doi-asserted-by":"crossref","first-page":"13147","DOI":"10.1073\/pnas.0405405101","article-title":"Structure\nof heptameric protective antigen bound to an anthrax toxin receptor:\nA role for receptor in pH-dependent pore formation","volume":"101","author":"Lacy","year":"2004","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit6","doi-asserted-by":"crossref","first-page":"614","DOI":"10.1016\/j.jmb.2009.07.037","article-title":"The protective antigen component of anthrax toxin forms\nfunctional octameric complexes","volume":"392","author":"Kintzer","year":"2009","journal-title":"J. Mol. Biol."},{"key":"2026090117324707200_cit7","doi-asserted-by":"crossref","first-page":"3453","DOI":"10.1073\/pnas.1000100107","article-title":"Three-dimensional\nstructure of the\nanthrax toxin pore inserted into lipid nanodiscs and lipid vesicles","volume":"107","author":"Katayama","year":"2010","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit8","doi-asserted-by":"crossref","first-page":"1445","DOI":"10.1021\/bi0119518","article-title":"PA63 channel of anthrax toxin: An\nextended \u03b2-barrel","volume":"41","author":"Nassi","year":"2002","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit9","doi-asserted-by":"crossref","first-page":"777","DOI":"10.1126\/science.1113380","article-title":"A phenylalanine clamp catalyzes protein\ntranslocation through the anthrax toxin pore","volume":"309","author":"Krantz","year":"2005","journal-title":"Science"},{"key":"2026090117324707200_cit10","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1038\/385833a0","article-title":"Crystal\nstructure of the anthrax toxin protective antigen","volume":"385","author":"Petosa","year":"1997","journal-title":"Nature"},{"key":"2026090117324707200_cit11","doi-asserted-by":"crossref","first-page":"1467","DOI":"10.1002\/pro.2136","article-title":"pH effects on binding between the anthrax protective\nantigen and the host cellular receptor CMG2","volume":"21","author":"Rajapaksha","year":"2012","journal-title":"Protein Sci."},{"key":"2026090117324707200_cit12","doi-asserted-by":"crossref","first-page":"3941","DOI":"10.1021\/bi972657b","article-title":"Identification of\nresidues lining the anthrax protective antigen channel","volume":"37","author":"Benson","year":"1998","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit13","doi-asserted-by":"crossref","first-page":"905","DOI":"10.1038\/nature02763","article-title":"Crystal\nstructure of a complex between anthrax toxin and its host cell receptor","volume":"430","author":"Santelli","year":"2004","journal-title":"Nature"},{"key":"2026090117324707200_cit14","doi-asserted-by":"crossref","first-page":"e329","DOI":"10.1371\/journal.pone.0000329","article-title":"Anthrax toxin receptor 2 determinants that dictate\nthe pH threshold of toxin pore formation","volume":"2","author":"Scobie","year":"2007","journal-title":"PLoS\nOne"},{"key":"2026090117324707200_cit15","doi-asserted-by":"crossref","first-page":"e1002354","DOI":"10.1371\/journal.ppat.1002354","article-title":"A receptor-based\nswitch that regulates anthrax toxin pore formation","volume":"7","author":"Pilpa","year":"2011","journal-title":"PLoS Pathog."},{"key":"2026090117324707200_cit16","doi-asserted-by":"crossref","first-page":"1047","DOI":"10.1021\/bi047791s","article-title":"Interaction of the\n20 kDa and 63 kDa fragments of anthrax protective antigen: Kinetics\nand thermodynamics","volume":"44","author":"Christensen","year":"2005","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit17","doi-asserted-by":"crossref","first-page":"12439","DOI":"10.1021\/bi030192l","article-title":"The kinetics\nof side chain stabilization during protein folding","volume":"42","author":"Frieden","year":"2003","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit18","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1016\/S0076-6879(04)80018-1","article-title":"The preparation of 19F-labeled\nproteins for NMR studies","volume":"380","author":"Frieden","year":"2004","journal-title":"Methods Enzymol."},{"key":"2026090117324707200_cit19","doi-asserted-by":"crossref","first-page":"14928","DOI":"10.1021\/bi701763z","article-title":"Effect\nof 2-fluorohistidine labeling of the anthrax protective antigen on\nstability, pore formation, and translocation","volume":"46","author":"Wimalasena","year":"2007","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit20","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1002\/pro.26","article-title":"Monitoring\nanthrax toxin receptor dissociation from\nthe protective antigen by NMR","volume":"18","author":"Rajapaksha","year":"2009","journal-title":"Protein Sci."},{"key":"2026090117324707200_cit21","doi-asserted-by":"crossref","first-page":"4322","DOI":"10.1021\/bi00067a022","article-title":"Engineered disulfide\nbonds as probes of the folding\npathway of barnase: Increasing the stability of proteins against the\nrate of denaturation","volume":"32","author":"Clarke","year":"1993","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit22","doi-asserted-by":"crossref","first-page":"709","DOI":"10.1073\/pnas.022649599","article-title":"Real-time and equilibrium 19F-NMR studies\nreveal the role of domain-domain interactions\nin the folding of the chaperone PapD","volume":"99","author":"Bann","year":"2002","journal-title":"Proc.\nNatl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit23","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1107\/S0021889887009737","article-title":"Automatic\nindexing of rotation diffraction patterns","volume":"21","author":"Kabsch","year":"1988","journal-title":"J.\nAppl. Crystallogr."},{"key":"2026090117324707200_cit24","first-page":"282","article-title":"An introduction\nto data reduction: Space-group determination, scaling and intensity\nstatistics","volume":"D67","author":"Evans","year":"2011","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit25","first-page":"22","article-title":"Molecular\nreplacement with MOLREP","volume":"D66","author":"Vagin","year":"2010","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit26","first-page":"213","article-title":"PHENIX: A comprehensive Python-based\nsystem for macromolecular structure solution","volume":"D66","author":"Adams","year":"2010","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit27","first-page":"486","article-title":"Features and development\nof Coot","volume":"D66","author":"Emsley","year":"2010","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit28","first-page":"439","article-title":"Optimal description of a protein\nstructure in terms\nof multiple groups undergoing TLS motion","volume":"D62","author":"Painter","year":"2006","journal-title":"Acta\nCrystallogr."},{"key":"2026090117324707200_cit29","first-page":"12","article-title":"MolProbity: All-atom structure validation for macromolecular\ncrystallography","volume":"D66","author":"Chen","year":"2010","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit30","first-page":"2288","article-title":"Developments\nin the CCP4 molecular-graphics project","volume":"D60","author":"Potterton","year":"2004","journal-title":"Acta\nCrystallogr."},{"key":"2026090117324707200_cit31","doi-asserted-by":"crossref","first-page":"10649","DOI":"10.1021\/bi990580g","article-title":"Atomic mutations at\nthe single tryptophan residue of human recombinant annexin V: Effects\non structure, stability, and activity","volume":"38","author":"Minks","year":"1999","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit32","doi-asserted-by":"crossref","first-page":"5502","DOI":"10.1021\/bi00184a019","article-title":"19F NMR\nspectroscopy of [6-19F]tryptophan-labeled Escherichia coli dihydrofolate reductase: Equilibrium\nfolding and ligand binding\nstudies","volume":"33","author":"Hoeltzli","year":"1994","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit33","doi-asserted-by":"crossref","first-page":"1467","DOI":"10.1002\/pro.2136","article-title":"pH effects on binding between the\nanthrax protective\nantigen and the host cellular receptor CMG2","volume":"21","author":"Rajapaksha","year":"2012","journal-title":"Protein Sci."},{"key":"2026090117324707200_cit34","doi-asserted-by":"crossref","first-page":"6973","DOI":"10.1021\/bi100647z","article-title":"Evidence that histidine protonation\nof receptor-bound anthrax protective antigen is a trigger for pore\nformation","volume":"49","author":"Wimalasena","year":"2010","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit35","doi-asserted-by":"crossref","first-page":"13803","DOI":"10.1073\/pnas.2436299100","article-title":"Mapping\ndominant-negative mutations of anthrax protective antigen by scanning\nmutagenesis","volume":"100","author":"Mourez","year":"2003","journal-title":"Proc. Natl. Acad. Sci. U.S.A."},{"key":"2026090117324707200_cit36","doi-asserted-by":"crossref","first-page":"4389","DOI":"10.1021\/ja0574825","article-title":"Site-directed parallel spin-labeling\nand paramagnetic relaxation enhancement in structure determination\nof membrane proteins by solution NMR spectroscopy","volume":"128","author":"Liang","year":"2006","journal-title":"J. Am. Chem. Soc."},{"key":"2026090117324707200_cit37","doi-asserted-by":"crossref","first-page":"2662","DOI":"10.1021\/bi301667u","article-title":"The denatured\nstate ensemble contains significant local and long-range structure\nunder native conditions: Analysis of the N-terminal domain of ribosomal\nprotein L9","volume":"52","author":"Meng","year":"2013","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit38","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1002\/pro.752","article-title":"Anthrax\ntoxin protective antigen: Insights into molecular switching from prepore\nto pore","volume":"21","author":"Bann","year":"2012","journal-title":"Protein Sci."},{"key":"2026090117324707200_cit39","doi-asserted-by":"crossref","first-page":"13775","DOI":"10.1021\/bi048614u","article-title":"Folding and domain-domain interactions of the chaperone\nPapD measured by 19F NMR","volume":"43","author":"Bann","year":"2004","journal-title":"Biochemistry"},{"key":"2026090117324707200_cit40","first-page":"72","article-title":"Scaling and\nassessment of data quality","volume":"D62","author":"Evans","year":"2006","journal-title":"Acta Crystallogr."},{"key":"2026090117324707200_cit41","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1038\/nsb0497-269","article-title":"Improved R-factors\nfor diffraction data analysis in\nmacromolecular crystallography","volume":"4","author":"Diederichs","year":"1997","journal-title":"Nat. Struct.\nBiol."},{"key":"2026090117324707200_cit42","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1107\/S0021889800018227","article-title":"Global\nindicators of X-ray data quality","volume":"34","author":"Weiss","year":"2001","journal-title":"J. Appl. Crystallogr."},{"key":"2026090117324707200_cit43","doi-asserted-by":"crossref","first-page":"1030","DOI":"10.1126\/science.1218231","article-title":"Linking crystallographic\nmodel and data quality","volume":"336","author":"Karplus","year":"2012","journal-title":"Science"},{"key":"2026090117324707200_cit44","doi-asserted-by":"crossref","first-page":"986","DOI":"10.1126\/science.1222162","article-title":"Biochemistry.\nResolving some old problems in protein crystallography","volume":"336","author":"Evans","year":"2012","journal-title":"Science"}],"container-title":["Biochemistry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/bi401405s","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/bichaw\/article-pdf\/53\/4\/690\/7871997\/bi401405s.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/bichaw\/article-pdf\/53\/4\/690\/7871997\/bi401405s.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T21:33:00Z","timestamp":1788298380000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/bichaw\/article\/53\/4\/690\/772724\/19F-Nuclear-Magnetic-Resonance-and"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,1,3]]},"references-count":44,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2014,1,3]]},"published-print":{"date-parts":[[2014,2,4]]}},"URL":"https:\/\/doi.org\/10.1021\/bi401405s","relation":{},"ISSN":["0006-2960","1520-4995"],"issn-type":[{"value":"0006-2960","type":"print"},{"value":"1520-4995","type":"electronic"}],"subject":[],"published":{"date-parts":[[2014,1,3]]}}}