title: Unique features of a Pseudomonas aeruginosa α2-macroglobulin homolog.
abstract: Human pathogens frequently use protein mimicry to manipulate host cells in order to promote their survival. Here we show that the opportunistic pathogen Pseudomonas aeruginosa synthesizes a structural homolog of the human α2-macroglobulin, a large-spectrum protease inhibitor and important player of innate immunity. Small-angle X-ray scattering analysis demonstrated that the fold of P. aeruginosa MagD (PA4489) is similar to that of the human macroglobulin and undergoes a conformational modification upon binding of human neutrophil elastase. MagD synthesis is under the control of a general virulence regulatory pathway including the inner membrane sensor RetS and the RNA-binding protein RsmA, and MagD undergoes cleavage from a 165-kDa to a 100-kDa form in all clinical isolates tested. Fractionation and immunoprecipitation experiments showed that MagD is translocated to the bacterial periplasm and resides within the inner membrane in a complex with three other molecular partners, MagA, MagB, and MagF, all of them encoded by the same six-gene genetic element. Inactivation of the whole 10-kb operon on the PAO1 genome resulted in mislocalization of uncleaved, in trans-provided MagD as well as its rapid degradation. Thus, pathogenic bacteria have acquired a homolog of human macroglobulin that plays roles in host-pathogen interactions potentially through recognition of host proteases and/or antimicrobial peptides; it is thus essential for bacterial defense.
  
  
  OBJECTIVE
  The pathogenesis of Pseudomonas aeruginosa is multifactorial and relies on surface-associated and secreted proteins with different toxic activities. Here we show that the bacterium synthesizes a 160-kDa structural homolog of the human large-spectrum protease inhibitor α2-macroglobulin. The bacterial protein is localized in the periplasm and is associated with the inner membrane through the formation of a multimolecular complex. Its synthesis is coregulated at the posttranscriptional level with other virulence determinants, suggesting that it has a role in bacterial pathogenicity and/or in defense against the host immune system. Thus, this new P. aeruginosa macromolecular complex may represent a future target for antibacterial developments.
authors.affiliation: Biologie du Cancer et de l'Infection (UMR-S1036) and Biologie à Grande Echelle (UMR1038), INSERM, Grenoble, France.
authors.forename: Mylène
authors.initials: M
authors.lastname: Robert-Genthon
authors.forename: Maria Guillermina
authors.initials: MG
authors.lastname: Casabona
authors.forename: David
authors.initials: D
authors.lastname: Neves
authors.forename: Yohann
authors.initials: Y
authors.lastname: Couté
authors.forename: Félix
authors.initials: F
authors.lastname: Cicéron
authors.forename: Sylvie
authors.initials: S
authors.lastname: Elsen
authors.forename: Andréa
authors.initials: A
authors.lastname: Dessen
authors.forename: Ina
authors.initials: I
authors.lastname: Attrée
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007155:Immunologic Factors / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D010196:Pancreatic Elastase / Q000378:metabolism; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000378:metabolism*; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D007155:Immunologic Factors; D011480:Protease Inhibitors; D010196:Pancreatic Elastase
references.citation: Mol Microbiol. 2012 Nov;86(4):921-36
references.pmid: 22957938
references.citation: J Biol Chem. 1979 Sep 10;254(17):8669-78
references.pmid: 89116
references.citation: J Biol Chem. 2010 Nov 12;285(46):35988-98
references.pmid: 20729192
references.citation: Gene. 1988 Dec 30;74(2):375-86
references.pmid: 3149945
references.citation: FEBS J. 2011 Feb;278(3):414-26
references.pmid: 21182592
references.citation: Environ Microbiol. 2003 Dec;5(12):1294-308
references.pmid: 14641575
references.citation: Horm Res. 1996;45(3-5):227-32
references.pmid: 8964589
references.citation: FEBS Lett. 1986 Sep 1;205(1):20-4
references.pmid: 2427362
references.citation: Dev Comp Immunol. 1999 Jun-Jul;23(4-5):375-90
references.pmid: 10426429
references.citation: Nature. 2011 Jul 20;475(7356):343-7
references.pmid: 21776080
references.citation: Res Microbiol. 2013 Jul-Aug;164(6):605-19
references.pmid: 23541478
references.citation: Mol Microbiol. 1992 May;6(9):1195-204
references.pmid: 1588818
references.citation: Proc Natl Acad Sci U S A. 2006 Jan 3;103(1):171-6
references.pmid: 16373506
references.citation: Environ Microbiol. 2011 Jul;13(7):1666-81
references.pmid: 21554516
references.citation: Curr Opin Struct Biol. 2010 Dec;20(6):749-55
references.pmid: 21030247
references.citation: Nucleic Acids Res. 2013 Jan;41(Database issue):D1063-9
references.pmid: 23203882
references.citation: Nature. 2006 Nov 9;444(7116):213-6
references.pmid: 17051160
references.citation: Mol Microbiol. 2009 May;72(3):612-32
references.pmid: 19426209
references.citation: Infect Immun. 2000 May;68(5):2916-24
references.pmid: 10768989
references.citation: Curr Issues Mol Biol. 2012;14(2):47-70
references.pmid: 22354680
references.citation: Nat Rev Microbiol. 2009 Sep;7(9):654-65
references.pmid: 19680249
references.citation: Science. 2012 Aug 17;337(6096):815
references.pmid: 22767897
references.citation: Genome Res. 2005 Feb;15(2):321-9
references.pmid: 15687295
references.citation: Genome Biol. 2004;5(6):R38
references.pmid: 15186489
references.citation: J Biol Chem. 1989 Feb 5;264(4):2350-6
references.pmid: 2464588
references.citation: Trends Microbiol. 2010 Dec;18(12):531-7
references.pmid: 20961764
references.citation: J Cell Physiol. 2013 Aug;228(8):1665-75
references.pmid: 23086799
references.citation: Biochem J. 2007 Oct 1;407(1):23-30
references.pmid: 17608619
references.citation: J Biol Chem. 2001 May 25;276(21):18437-41
references.pmid: 11278658
references.citation: J Bacteriol. 2006 Jan;188(1):132-40
references.pmid: 16352829
references.citation: Proteomics. 2013 Aug;13(16):2419-23
references.pmid: 23744604
references.citation: Microbiology (Reading). 1998 Dec;144 ( Pt 12):3379-3386
references.pmid: 9884230
references.citation: Biochem J. 2004 Apr 1;379(Pt 1):107-18
references.pmid: 14705961
references.citation: Infect Immun. 1999 Nov;67(11):6164-7
references.pmid: 10531282
references.citation: PLoS One. 2012;7(4):e35384
references.pmid: 22530012
references.citation: Angew Chem Int Ed Engl. 2012 Apr 2;51(14):3340-4
references.pmid: 22290936
references.citation: J Biol Chem. 1989 Sep 25;264(27):15781-9
references.pmid: 2476433
references.citation: J Biol Chem. 2009 Jun 5;284(23):15762-70
references.pmid: 19369699
references.citation: Protein Sci. 2000 Oct;9(10):1889-97
references.pmid: 11106161
references.citation: Nature. 2000 Aug 31;406(6799):959-64
references.pmid: 10984043
references.citation: Biophys J. 2001 Jun;80(6):2946-53
references.pmid: 11371467
references.citation: Proteomics. 2009 Apr;9(7):1901-15
references.pmid: 19333994
references.citation: Electron Microsc Rev. 1992;5(2):231-81
references.pmid: 1374655
references.citation: Angew Chem Int Ed Engl. 2012 May 21;51(21):5045-7
references.pmid: 22488953
references.citation: Environ Microbiol. 2013 Feb;15(2):471-86
references.pmid: 22765374
references.citation: Dev Cell. 2004 Nov;7(5):745-54
references.pmid: 15525535
references.citation: J Biol Chem. 2008 Oct 17;283(42):28747-56
references.pmid: 18697741
references.citation: J Appl Crystallogr. 2009 Apr 1;42(Pt 2):342-346
references.pmid: 27630371
references.citation: Immunol Rev. 1998 Dec;166:15-26
references.pmid: 9914899
references.citation: Nucleic Acids Res. 2011 Jan;39(Database issue):D596-600
references.pmid: 20929876
references.citation: Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6394-9
references.pmid: 17405861
references.citation: J Struct Biol. 2000 Jul;131(1):19-26
references.pmid: 10945966