2qff: Difference between revisions

Revision as of 19:39, 21 February 2008

Crystal structure of Staphylococcal Complement Inhibitor

OverviewOverview

The pathogenic bacterium Staphylococcus aureus counteracts the host immune defense by excretion of the 85 residue staphylococcal complement inhibitor (SCIN). SCIN inhibits the central complement convertases; thereby, it reduces phagocytosis following opsonization and efficiently blocks all downstream effector functions. In this study, we present the crystal structure of SCIN at 1.8 A resolution and the identification of its active site. Functional characterization of structure based chimeric proteins, consisting of SCIN and the structurally but nonfunctional homologue open reading frame-D, indicate an 18-residue segment (Leu-31-Gly-48) crucial for SCIN activity. In all complement activation pathways, chimeras lacking these SCIN residues completely fail to inhibit production of the potent mediator of inflammation C5a. Inhibition of alternative pathway-mediated opsonization (C3b deposition) and formation of the lytic membrane attack complex (C5b-9 deposition) are strongly reduced for these chimeras as well. For inhibition of the classical/lectin pathway-mediated C3b and C5b-9 deposition, the same residues are critical although additional sites are involved. These chimeras also display reduced capacity to stabilize the C3 convertases of both the alternative and the classical/lectin pathway indicating the stabilizing effect is pivotal for the complement inhibitory activity of SCIN. Because SCIN specifically and efficiently inhibits complement, it has a high potential in anti-inflammatory therapy. Our data are a first step toward the development of a second generation molecule suitable for such therapeutic complement intervention.

About this StructureAbout this Structure

2QFF is a Single protein structure of sequence from Staphylococcus aureus. Full crystallographic information is available from OCA.

ReferenceReference

Staphylococcal complement inhibitor: structure and active sites., Rooijakkers SH, Milder FJ, Bardoel BW, Ruyken M, van Strijp JA, Gros P, J Immunol. 2007 Sep 1;179(5):2989-98. PMID:17709514

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 ==Overview==
-The pathogenic bacterium Staphylococcus aureus counteracts the host immune, defense by excretion of the 85 residue staphylococcal complement inhibitor, (SCIN). SCIN inhibits the central complement convertases; thereby, it, reduces phagocytosis following opsonization and efficiently blocks all, downstream effector functions. In this study, we present the crystal, structure of SCIN at 1.8 A resolution and the identification of its active, site. Functional characterization of structure based chimeric proteins, consisting of SCIN and the structurally but nonfunctional homologue open, reading frame-D, indicate an 18-residue segment (Leu-31-Gly-48) crucial, for SCIN activity. In all complement activation pathways, chimeras lacking, these SCIN residues completely fail to inhibit production of the potent, mediator of inflammation C5a. Inhibition of alternative pathway-mediated, opsonization (C3b deposition) and formation of the lytic membrane attack, complex (C5b-9 deposition) are strongly reduced for these chimeras as, well. For inhibition of the classical/lectin pathway-mediated C3b and, C5b-9 deposition, the same residues are critical although additional sites, are involved. These chimeras also display reduced capacity to stabilize, the C3 convertases of both the alternative and the classical/lectin, pathway indicating the stabilizing effect is pivotal for the complement, inhibitory activity of SCIN. Because SCIN specifically and efficiently, inhibits complement, it has a high potential in anti-inflammatory therapy., Our data are a first step toward the development of a second generation, molecule suitable for such therapeutic complement intervention.
+The pathogenic bacterium Staphylococcus aureus counteracts the host immune defense by excretion of the 85 residue staphylococcal complement inhibitor (SCIN). SCIN inhibits the central complement convertases; thereby, it reduces phagocytosis following opsonization and efficiently blocks all downstream effector functions. In this study, we present the crystal structure of SCIN at 1.8 A resolution and the identification of its active site. Functional characterization of structure based chimeric proteins, consisting of SCIN and the structurally but nonfunctional homologue open reading frame-D, indicate an 18-residue segment (Leu-31-Gly-48) crucial for SCIN activity. In all complement activation pathways, chimeras lacking these SCIN residues completely fail to inhibit production of the potent mediator of inflammation C5a. Inhibition of alternative pathway-mediated opsonization (C3b deposition) and formation of the lytic membrane attack complex (C5b-9 deposition) are strongly reduced for these chimeras as well. For inhibition of the classical/lectin pathway-mediated C3b and C5b-9 deposition, the same residues are critical although additional sites are involved. These chimeras also display reduced capacity to stabilize the C3 convertases of both the alternative and the classical/lectin pathway indicating the stabilizing effect is pivotal for the complement inhibitory activity of SCIN. Because SCIN specifically and efficiently inhibits complement, it has a high potential in anti-inflammatory therapy. Our data are a first step toward the development of a second generation molecule suitable for such therapeutic complement intervention.
 ==About this Structure==
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 [[Category: Single protein]]
 [[Category: Staphylococcus aureus]]
-[[Category: Bardoel, B.W.]]
+[[Category: Bardoel, B W.]]
 [[Category: Gros, P.]]
-[[Category: Milder, F.J.]]
+[[Category: Milder, F J.]]
-[[Category: Rooijakkers, S.H.M.]]
+[[Category: Rooijakkers, S H.M.]]
 [[Category: Ruyken, M.]]
-[[Category: Strijp, J.A.G.Van.]]
+[[Category: Strijp, J A.G Van.]]
 [[Category: bacterial]]
 [[Category: complement]]
@@ Line 26: / Line 26: @@
 [[Category: molecular biology]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 13:46:40 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:38:56 2008''