title: Shr of group A streptococcus is a new type of composite NEAT protein involved in sequestering haem from methaemoglobin.
abstract: A growing body of evidence suggests that surface or secreted proteins with NEAr Transporter (NEAT) domains play a central role in haem acquisition and trafficking across the cell envelope of Gram-positive bacteria. Group A streptococcus (GAS), a β-haemolytic human pathogen, expresses a NEAT protein, Shr, which binds several haemoproteins and extracellular matrix (ECM) components. Shr is a complex, membrane-anchored protein, with a unique N-terminal domain (NTD) and two NEAT domains separated by a central leucine-rich repeat region. In this study we have carried out an analysis of the functional domains in Shr. We show that Shr obtains haem in solution and furthermore reduces the haem iron; this is the first report of haem reduction by a NEAT protein. More specifically, we demonstrate that both of the constituent NEAT domains of Shr are responsible for binding haem, although they are missing a critical tyrosine residue found in the ligand-binding pocket of other haem-binding NEAT domains. Further investigations show that a previously undescribed region within the Shr NTD interacts with methaemoglobin. Shr NEAT domains, however, do not contribute significantly to the binding of methaemoglobin but mediate binding to the ECM components fibronectin and laminin. A protein fragment containing the NTD plus the first NEAT domain was found to be sufficient to sequester haem directly from methaemoglobin. Correlating these in vitro findings to in vivo biological function, mutants analysis establishes the role of Shr in GAS growth with methaemoglobin as a sole source of iron, and indicates that at least one NEAT domain is necessary for the utilization of methaemoglobin. We suggest that Shr is the prototype of a new group of NEAT composite proteins involved in haem uptake found in pyogenic streptococci and Clostridium novyi.
authors.affiliation: Department of Biology,College of Arts and Sciences, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Mahamoudou
authors.initials: M
authors.lastname: Ouattara
authors.forename: Elizabeth Bentley
authors.initials: EB
authors.lastname: Cunha
authors.forename: Xueru
authors.initials: X
authors.lastname: Li
authors.forename: Ya-Shu
authors.initials: YS
authors.lastname: Huang
authors.forename: Dabney
authors.initials: D
authors.lastname: Dixon
authors.forename: Zehava
authors.initials: Z
authors.lastname: Eichenbaum
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001692:Biological Transport; D003013:Clostridium / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D006801:Humans; D008706:Methemoglobin / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013290:Streptococcal Infections / Q000378:metabolism / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006418:Heme; D008706:Methemoglobin
references.citation: Biochem J. 1969 Nov;115(2):279-85
references.pmid: 5378383
references.citation: Mol Microbiol. 2006 Feb;59(4):1185-98
references.pmid: 16430693
references.citation: J Biol Chem. 2008 Nov 14;283(46):31591-600
references.pmid: 18715872
references.citation: J Inorg Biochem. 2010 Mar;104(3):341-8
references.pmid: 19853304
references.citation: J Biol Chem. 2008 Oct 17;283(42):28649-59
references.pmid: 18667422
references.citation: Infect Immun. 1996 Dec;64(12):5428-9
references.pmid: 8945602
references.citation: Infect Immun. 2003 Oct;71(10):5962-9
references.pmid: 14500516
references.citation: J Biol Chem. 2009 Jan 9;284(2):1166-76
references.pmid: 18984582
references.citation: Infect Immun. 2003 Mar;71(3):1042-55
references.pmid: 12595414
references.citation: J Biol Chem. 2005 Apr 22;280(16):16263-71
references.pmid: 15718231
references.citation: PLoS Pathog. 2009 Nov;5(11):e1000675
references.pmid: 19956654
references.citation: Mol Microbiol. 2001 Jan;39(1):1-11
references.pmid: 11123683
references.citation: J Biol Chem. 1998 Jan 9;273(2):837-41
references.pmid: 9422739
references.citation: Mol Microbiol. 2008 Nov;70(4):983-99
references.pmid: 18826411
references.citation: Genome Biol. 2002 Aug 15;3(9):RESEARCH0047
references.pmid: 12225586
references.citation: J Mol Biol. 2007 Nov 23;374(2):374-83
references.pmid: 17920629
references.citation: Mol Microbiol. 2004 Mar;51(5):1509-19
references.pmid: 14982642
references.citation: Biochemistry. 2008 Feb 26;47(8):2678-88
references.pmid: 18247478
references.citation: Mol Microbiol. 2007 Jan;63(1):139-49
references.pmid: 17229211
references.citation: Proteins. 2006 Nov 15;65(3):643-55
references.pmid: 16981205
references.citation: J Biol Chem. 2005 Jan 28;280(4):2840-6
references.pmid: 15520015
references.citation: IUBMB Life. 2005 Nov;57(11):749-59
references.pmid: 16511968
references.citation: Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):2293-8
references.pmid: 11830639
references.citation: FEMS Microbiol Lett. 2003 Apr 11;221(1):103-10
references.pmid: 12694917
references.citation: J Bacteriol. 2009 Apr;191(8):2638-48
references.pmid: 19201805
references.citation: Am J Hematol. 2007 Feb;82(2):134-44
references.pmid: 16986127
references.citation: BMC Microbiol. 2008 Jan 23;8:15
references.pmid: 18215300
references.citation: J Bacteriol. 2007 Jan;189(1):254-64
references.pmid: 17041047
references.citation: Infect Immun. 1999 Aug;67(8):3879-92
references.pmid: 10417152
references.citation: Biochemistry. 2006 Oct 24;45(42):12867-75
references.pmid: 17042505
references.citation: J Bacteriol. 2007 May;189(9):3650-4
references.pmid: 17322319
references.citation: Microbiology (Reading). 2005 Nov;151(Pt 11):3749-3757
references.pmid: 16272396
references.citation: Trends Microbiol. 2002 Feb;10(2):87-93
references.pmid: 11827810
references.citation: Rev Infect Dis. 1981 Nov-Dec;3(6):1127-38
references.pmid: 7043704
references.citation: Nucleic Acids Res. 2009 Jan;37(Database issue):D229-32
references.pmid: 18978020
references.citation: Biochem Soc Trans. 2008 Dec;36(Pt 6):1138-43
references.pmid: 19021512
references.citation: J Biol Chem. 2007 Apr 6;282(14):10625-31
references.pmid: 17287214
references.citation: Appl Environ Microbiol. 1998 Aug;64(8):2763-9
references.pmid: 9687428
references.citation: Biochem J. 1979 May 1;179(2):281-9
references.pmid: 486081
references.citation: Mol Microbiol. 1996 May;20(4):725-39
references.pmid: 9026634
references.citation: DNA Cell Biol. 2002 Apr;21(4):281-95
references.pmid: 12042068
references.citation: Arch Biochem Biophys. 2009 Jan 1;481(1):1-15
references.pmid: 18977196
references.citation: J Mol Biol. 2006 Jul 7;360(2):435-47
references.pmid: 16762363
references.citation: PLoS Pathog. 2009 Mar;5(3):e1000346
references.pmid: 19325880
references.citation: Mol Microbiol. 2000 Apr;36(1):68-84
references.pmid: 10760164
references.citation: Annu Rev Microbiol. 2004;58:611-47
references.pmid: 15487950
references.citation: Int J Biochem. 1985;17(7):767-73
references.pmid: 3902529
references.citation: Curr Opin Struct Biol. 2001 Dec;11(6):725-32
references.pmid: 11751054
references.citation: Microbes Infect. 2004 Apr;6(4):390-7
references.pmid: 15101396
references.citation: Mol Microbiol. 2003 Jul;49(1):37-53
references.pmid: 12823809
references.citation: Microbiology (Reading). 2010 Jun;156(Pt 6):1824-1835
references.pmid: 20223800
references.citation: Infect Immun. 2008 Nov;76(11):5006-15
references.pmid: 18710861
references.citation: J Inorg Biochem. 2008 Mar;102(3):480-8
references.pmid: 18194816
references.citation: J Bacteriol. 2006 Dec;188(24):8421-9
references.pmid: 17041042
references.citation: J Biochem. 1964 Dec;56:594-600
references.pmid: 14244064
references.citation: J Biol Chem. 2004 Jan 2;279(1):436-43
references.pmid: 14570922
references.citation: J Bacteriol. 2006 Dec;188(23):8145-52
references.pmid: 17012401
references.citation: Proc Natl Acad Sci U S A. 1998 May 26;95(11):5857-64
references.pmid: 9600884
references.citation: Science. 2003 Feb 7;299(5608):906-9
references.pmid: 12574635