title: Integrin engagement by the helical RGD motif of the Helicobacter pylori CagL protein is regulated by pH-induced displacement of a neighboring helix.
abstract: Arginine-aspartate-glycine (RGD) motifs are recognized by integrins to bridge cells to one another and the extracellular matrix. RGD motifs typically reside in exposed loop conformations. X-ray crystal structures of the Helicobacter pylori protein CagL revealed that RGD motifs can also exist in helical regions of proteins. Interactions between CagL and host gastric epithelial cell via integrins are required for the translocation of the bacterial oncoprotein CagA. Here, we have investigated the molecular basis of the CagL-host cell interactions using structural, biophysical, and functional analyses. We solved an x-ray crystal structure of CagL that revealed conformational changes induced by low pH not present in previous structures. Using analytical ultracentrifugation, we found that pH-induced conformational changes in CagL occur in solution and not just in the crystalline environment. By designing numerous CagL mutants based on all available crystal structures, we probed the functional roles of CagL conformational changes on cell surface integrin engagement. Together, our data indicate that the helical RGD motif in CagL is buried by a neighboring helix at low pH to inhibit CagL binding to integrin, whereas at neutral pH the neighboring helix is displaced to allow integrin access to the CagL RGD motif. This novel molecular mechanism of regulating integrin-RGD motif interactions by changes in the chemical environment provides new insight to H. pylori-mediated oncogenesis.
authors.affiliation: From the Institute of Human Virology and.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bonsor
authors.affiliation: the Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität, 80336 München, Germany.
authors.forename: Kieu T
authors.initials: KT
authors.lastname: Pham
authors.affiliation: From the Institute of Human Virology and.
authors.forename: Robert
authors.initials: R
authors.lastname: Beadenkopf
authors.affiliation: the Department of Biology, University of Konstanz, Konstanz D-78457, Germany.
authors.forename: Kay
authors.initials: K
authors.lastname: Diederichs
authors.affiliation: the Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität, 80336 München, Germany, the German Center for Infection Research (DZIF), LMU Munich, München, Germany, and.
authors.forename: Rainer
authors.initials: R
authors.lastname: Haas
authors.affiliation: the Department of Chemistry and Biochemistry, University of Maryland College Park, College Park, Maryland 20742.
authors.forename: Dorothy
authors.initials: D
authors.lastname: Beckett
authors.affiliation: the Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität, 80336 München, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fischer
authors.affiliation: From the Institute of Human Virology and the Departments of Medicine and Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201, esundberg@ihv.umaryland.edu.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sundberg
mesh_terms: D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002471:Cell Transformation, Neoplastic; D018360:Crystallography, X-Ray; D016480:Helicobacter pylori / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; C568315:cagL protein, Helicobacter pylori
keywords: Helicobacter pylori; analytical ultracentrifugation; conformational change; integrin; x-ray crystallography
references.citation: Nature. 2011 Jun 16;474(7351):343-9
references.pmid: 21677751
references.citation: Science. 1998 Jan 16;279(5349):373-7
references.pmid: 9430586
references.citation: Mol Carcinog. 2011 Oct;50(10):751-9
references.pmid: 21374738
references.citation: PLoS Pathog. 2011 Sep;7(9):e1002237
references.pmid: 21909278
references.citation: Acta Crystallogr D Biol Crystallogr. 2011 Nov;67(Pt 11):915-9
references.pmid: 22101817
references.citation: PLoS One. 2012;7(4):e35341
references.pmid: 22493745
references.citation: Gut. 2012 Jul;61(7):986-96
references.pmid: 22287591
references.citation: Amino Acids. 2012 Jul;43(1):219-32
references.pmid: 21915696
references.citation: FASEB J. 2012 Aug;26(8):3412-20
references.pmid: 22601780
references.citation: Structure. 2013 Nov 5;21(11):1931-41
references.pmid: 24076404
references.citation: J Biol Chem. 2014 Mar 7;289(10):6332-40
references.pmid: 24375407
references.citation: Acta Crystallogr D Biol Crystallogr. 2014 May;70(Pt 5):1391-400
references.pmid: 24816107
references.citation: PLoS One. 2014;9(6):e97782
references.pmid: 24893039
references.citation: Cell Microbiol. 2013 Apr;15(4):554-70
references.pmid: 23107019
references.citation: Nat Struct Mol Biol. 2014 Dec;21(12):1091-6
references.pmid: 25383667
references.citation: J Mol Biol. 2015 Mar 27;427(6 Pt B):1304-15
references.pmid: 25617764
references.citation: Am J Pathol. 2000 May;156(5):1489-98
references.pmid: 10793060
references.citation: Cell Microbiol. 2001 Jan;3(1):21-31
references.pmid: 11207617
references.citation: Mol Microbiol. 2001 Dec;42(5):1337-48
references.pmid: 11886563
references.citation: Nat Rev Cancer. 2002 Jan;2(1):28-37
references.pmid: 11902583
references.citation: N Engl J Med. 2002 Oct 10;347(15):1175-86
references.pmid: 12374879
references.citation: Bioinformatics. 2003 Sep 22;19(14):1852-3
references.pmid: 14512360
references.citation: Physiology (Bethesda). 2004 Aug;19:207-15
references.pmid: 15304635
references.citation: Proc Natl Acad Sci U S A. 1972 Dec;69(12):3506-9
references.pmid: 4509307
references.citation: Biophys J. 1981 Dec;36(3):575-88
references.pmid: 7326325
references.citation: Proc Natl Acad Sci U S A. 1991 Jan 15;88(2):345-9
references.pmid: 1988935
references.citation: Proc Natl Acad Sci U S A. 1999 Jan 5;96(1):242-7
references.pmid: 9874803
references.citation: Anal Biochem. 2006 Jul 15;354(2):238-46
references.pmid: 16730633
references.citation: Anal Biochem. 2006 Oct 15;357(2):289-98
references.pmid: 16962548
references.citation: Cell Microbiol. 2007 Oct;9(10):2457-69
references.pmid: 17517062
references.citation: Nat Protoc. 2007;2(9):2212-21
references.pmid: 17853878
references.citation: Nature. 2007 Oct 18;449(7164):862-6
references.pmid: 17943123
references.citation: Biochem Biophys Res Commun. 1992 Feb 14;182(3):1025-31
references.pmid: 1540151
references.citation: Anal Biochem. 1992 Jun;203(2):295-301
references.pmid: 1416025
references.citation: Cell. 1992 Nov 13;71(4):671-8
references.pmid: 1423622
references.citation: J Clin Gastroenterol. 1993;17 Suppl 1:S70-7
references.pmid: 8283018
references.citation: J Cell Biol. 1994 Feb;124(4):619-26
references.pmid: 8106557
references.citation: Proc Natl Acad Sci U S A. 1994 Mar 1;91(5):1932-6
references.pmid: 8127909
references.citation: Cancer Res. 1995 May 15;55(10):2111-5
references.pmid: 7743510
references.citation: Microbiol Res. 2009;164(2):180-90
references.pmid: 17449233
references.citation: Cell Tissue Res. 2010 Jan;339(1):269-80
references.pmid: 19693543
references.citation: Endocrinology. 1946 Jul;39:8-13
references.pmid: 20996015
references.citation: Cell. 1996 Jan 12;84(1):155-64
references.pmid: 8548820
references.citation: Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14648-53
references.pmid: 8962108
references.citation: Gut. 1997 Mar;40(3):297-301
references.pmid: 9135515
references.citation: Biophys J. 2011 Aug 17;101(4):892-8
references.pmid: 21843480