title: Influence of oligomerization state on the structural properties of invasion plasmid antigen B from Shigella flexneri in the presence and absence of phospholipid membranes.
abstract: Shigella flexneri causes bacillary dysentery, an important cause of mortality among children in the developing world. Shigella secretes effector proteins via its type III secretion system (T3SS) to promote bacterial uptake into human colonic epithelial cells. The T3SS basal body spans the bacterial cell envelope anchoring a surface-exposed needle. A pentamer of invasion plasmid antigen D lies at the nascent needle tip and invasion plasmid antigen B (IpaB) is recruited into the needle tip complex on exposure to bile salts. From here, IpaB forms a translocon pore in the host cell membrane. Although the mechanism by which IpaB inserts into the membrane is unknown, it was recently shown that recombinant IpaB can exist as either a monomer or tetramer. Both of these forms of IpaB associate with membranes, however, only the tetramer forms pores in liposomes. To reveal differences between these membrane-binding events, Cys mutations were introduced throughout IpaB, allowing site-specific fluorescence labeling. Fluorescence quenching was used to determine the influence of oligomerization and/or membrane association on the accessibility of different IpaB regions to small solutes. The data show that the hydrophobic region of tetrameric IpaB is more accessible to solvent relative to the monomer. The hydrophobic region appears to promote membrane interaction for both forms of IpaB, however, more of the hydrophobic region is protected from solvent for the tetramer after membrane association. Limited proteolysis demonstrated that changes in IpaB's oligomeric state may determine the manner by which it associates with phospholipid membranes and the subsequent outcome of this association.
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, 74078.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Adam
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Dickenson
authors.forename: Jamie C
authors.initials: JC
authors.lastname: Greenwood
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Picking
authors.forename: William D
authors.initials: WD
authors.lastname: Picking
mesh_terms: D019943:Amino Acid Substitution; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003545:Cysteine / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005456:Fluorescent Dyes / Q000737:chemistry; D006367:HeLa Cells / Q000382:microbiology; D006461:Hemolysis; D054884:Host-Pathogen Interactions; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010743:Phospholipids / Q000737:chemistry; D012763:Shigella flexneri / Q000472:pathogenicity
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D005456:Fluorescent Dyes; D008081:Liposomes; D018832:Molecular Chaperones; D010743:Phospholipids; C087447:ipaB protein, Shigella; C094580:IpgC protein, Shigella; D003545:Cysteine
keywords: Shigella; Stern-Volmer; fluorescence quenching; membrane; protein-lipid
references.citation: Protein Sci. 2006 Mar;15(3):543-52
references.pmid: 16501225
references.citation: Infect Immun. 2012 Mar;80(3):1222-31
references.pmid: 22202122
references.citation: J Biol Chem. 2009 Jun 12;284(24):16126-16134
references.pmid: 19357078
references.citation: Curr Opin Microbiol. 2003 Feb;6(1):7-14
references.pmid: 12615213
references.citation: J Mol Biol. 2012 Apr 13;417(5):395-405
references.pmid: 22321794
references.citation: Cell Death Dis. 2012 Sep 06;3:e384
references.pmid: 22951981
references.citation: Mol Microbiol. 2001 Feb;39(3):652-63
references.pmid: 11169106
references.citation: Protein Sci. 2013 May;22(5):614-27
references.pmid: 23456854
references.citation: Infect Immun. 2010 Apr;78(4):1682-91
references.pmid: 20086081
references.citation: Microb Pathog. 2008 Oct;45(4):282-9
references.pmid: 18656530
references.citation: Biol Chem. 2010 Jul;391(7):745-51
references.pmid: 20482311
references.citation: Infect Immun. 2009 Jul;77(7):2754-61
references.pmid: 19433542
references.citation: Infect Immun. 2003 Mar;71(3):1255-64
references.pmid: 12595440
references.citation: Infect Immun. 2006 Aug;74(8):4391-400
references.pmid: 16861624
references.citation: PLoS Pathog. 2009 Jan;5(1):e1000271
references.pmid: 19165331
references.citation: Proteins. 2012 Mar;80(3):935-45
references.pmid: 22423359
references.citation: Mol Microbiol. 2007 Mar;63(6):1719-30
references.pmid: 17367391
references.citation: J Mol Biol. 2012 Jun 29;420(1-2):29-39
references.pmid: 22480614
references.citation: Mol Microbiol. 2001 Jan;39(1):100-11
references.pmid: 11123692
references.citation: Biochemistry. 2012 May 15;51(19):4062-71
references.pmid: 22497344
references.citation: Mol Microbiol. 2003 Jul;49(2):425-39
references.pmid: 12828640
references.citation: Mol Microbiol. 2008 Jun;68(5):1085-95
references.pmid: 18430138
references.citation: Clin Microbiol Rev. 2008 Jan;21(1):134-56
references.pmid: 18202440
references.citation: J Cell Biol. 1999 Nov 1;147(3):683-93
references.pmid: 10545510
references.citation: Biochemistry. 1998 Dec 22;37(51):17642-50
references.pmid: 9922129
references.citation: Biochemistry. 2011 Jan 18;50(2):172-80
references.pmid: 21126091
references.citation: Infect Immun. 2007 May;75(5):2626-9
references.pmid: 17296762
references.citation: Biochemistry. 2007 Jul 10;46(27):8128-37
references.pmid: 17571858
references.citation: J Biol Chem. 2008 Jul 4;283(27):18646-54
references.pmid: 18450744
references.citation: Mol Microbiol. 2005 May;56(3):590-603
references.pmid: 15819617
references.citation: J Biol Chem. 2010 Dec 17;285(51):39965-75
references.pmid: 20937829