title: Structural basis of chaperone recognition of type III secretion system minor translocator proteins.
abstract: The type III secretion system (T3SS) is a complex nanomachine employed by many Gram-negative pathogens, including the nosocomial agent Pseudomonas aeruginosa, to inject toxins directly into the cytoplasm of eukaryotic cells. A key component of all T3SS is the translocon, a proteinaceous channel that is inserted into the target membrane, which allows passage of toxins into target cells. In most bacterial species, two distinct membrane proteins (the "translocators") are involved in translocon formation, whereas in the bacterial cytoplasm, however, they remain associated to a common chaperone. To date, the strategy employed by a single chaperone to recognize two distinct translocators is unknown. Here, we report the crystal structure of a complex between the Pseudomonas translocator chaperone PcrH and a short region from the minor translocator PopD. PcrH displays a 7-helical tetratricopeptide repeat fold that harbors the PopD peptide within its concave region, originally believed to be involved in recognition of the major translocator, PopB. Point mutations introduced into the PcrH-interacting region of PopD impede translocator-chaperone recognition in vitro and lead to impairment of bacterial cytotoxicity toward macrophages in vivo. These results indicate that T3SS translocator chaperones form binary complexes with their partner molecules, and the stability of their interaction regions must be strictly maintained to guarantee bacterial infectivity. The PcrH-PopD complex displays homologs among a number of pathogenic strains and could represent a novel, potential target for antibiotic development.
authors.affiliation: Bacterial Pathogenesis Group, Institut de Biologie Structurale, UMR 5075, CNRS/Commissariat à l'Enérgie Atomique/Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble, France.
authors.forename: Viviana
authors.initials: V
authors.lastname: Job
authors.forename: Pierre-Jean
authors.initials: PJ
authors.lastname: Matteï
authors.forename: David
authors.initials: D
authors.lastname: Lemaire
authors.forename: Ina
authors.initials: I
authors.lastname: Attree
authors.forename: Andréa
authors.initials: A
authors.lastname: Dessen
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D042541:Intracellular Space / Q000378:metabolism; D008264:Macrophages / Q000382:microbiology; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D020449:Repetitive Sequences, Amino Acid; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments
references.citation: J Biol Chem. 2005 Oct 28;280(43):36293-300
references.pmid: 16115870
references.citation: Curr Opin Microbiol. 2003 Feb;6(1):7-14
references.pmid: 12615213
references.citation: FEMS Microbiol Lett. 2006 Mar;256(1):57-66
references.pmid: 16487320
references.citation: J Mol Biol. 2008 Mar 28;377(3):819-30
references.pmid: 18281060
references.citation: Mol Microbiol. 1999 Jan;31(1):143-56
references.pmid: 9987117
references.citation: Infect Immun. 2004 Aug;72(8):4741-50
references.pmid: 15271936
references.citation: Proc Natl Acad Sci U S A. 2000 Aug 29;97(18):10225-30
references.pmid: 10944190
references.citation: Proc Natl Acad Sci U S A. 2000 Sep 26;97(20):11008-13
references.pmid: 10984518
references.citation: EMBO J. 2003 Oct 1;22(19):4957-67
references.pmid: 14517235
references.citation: Mol Microbiol. 2001 Apr;40(1):76-85
references.pmid: 11298277
references.citation: J Appl Crystallogr. 2007 Aug 1;40(Pt 4):658-674
references.pmid: 19461840
references.citation: Proc Natl Acad Sci U S A. 2007 May 8;104(19):7803-8
references.pmid: 17470796
references.citation: Nat Rev Microbiol. 2006 Nov;4(11):811-25
references.pmid: 17041629
references.citation: Trends Microbiol. 2002 Apr;10(4):186-92
references.pmid: 11912026
references.citation: Acta Crystallogr D Biol Crystallogr. 1997 May 1;53(Pt 3):240-55
references.pmid: 15299926
references.citation: Nucleic Acids Res. 2007 Jul;35(Web Server issue):W375-83
references.pmid: 17452350
references.citation: Mol Microbiol. 2001 Feb;39(3):652-63
references.pmid: 11169106
references.citation: FEBS J. 2007 Jul;274(14):3601-3610
references.pmid: 17578515
references.citation: Microbiol Mol Biol Rev. 2004 Dec;68(4):771-95
references.pmid: 15590783
references.citation: Biochemistry. 2006 Jul 4;45(26):8117-23
references.pmid: 16800636
references.citation: Nat Struct Biol. 2001 Dec;8(12):1031-6
references.pmid: 11685226
references.citation: Proc Natl Acad Sci U S A. 2009 Jun 16;106(24):9661-6
references.pmid: 19478065
references.citation: Mol Microbiol. 2008 Jun;68(5):1085-95
references.pmid: 18430138
references.citation: Mol Cell. 2002 May;9(5):971-80
references.pmid: 12049734
references.citation: Proc Natl Acad Sci U S A. 2006 Aug 15;103(33):12529-33
references.pmid: 16888041
references.citation: Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 1):2126-32
references.pmid: 15572765
references.citation: Physiology (Bethesda). 2005 Oct;20:326-39
references.pmid: 16174872
references.citation: Nature. 2001 Nov 1;414(6859):77-81
references.pmid: 11689946
references.citation: Mol Cell. 2006 Mar 3;21(5):653-64
references.pmid: 16507363
references.citation: Mol Microbiol. 2003 Jan;47(1):209-21
references.pmid: 12492865
references.citation: J Mol Biol. 2008 Jan 25;375(4):997-1012
references.pmid: 18054956
references.citation: Nature. 2006 Jun 1;441(7093):637-40
references.pmid: 16738660
references.citation: Mol Microbiol. 2006 Jan;59(1):31-44
references.pmid: 16359316
references.citation: Cell Host Microbe. 2009 Jun 18;5(6):571-9
references.pmid: 19527884
references.citation: FEMS Microbiol Lett. 2003 Jun 6;223(1):53-60
references.pmid: 12799000
references.citation: Science. 2005 Oct 28;310(5748):674-6
references.pmid: 16254184
references.citation: Infect Immun. 2006 Aug;74(8):4391-400
references.pmid: 16861624