PDBsum entry: 3kls

Immune system

PDB id: 3kls

Contents

Protein chains

1622 a.a. *

191 a.a. *

1478 a.a. *

Ligands

NAG-NAG ×2

NAG ×2

Metals

_CD ×9

* Residue conservation analysis

PDB id:

3kls

Name:

Immune system

Title:

Structure of complement c5 in complex with ssl7

Structure:

Complement c5. Chain: a, b. Synonym: c3 and pzp-like alpha-2-macroglobulin domain-conta protein 4, complement c5 beta chain, complement c5 alpha ch anaphylatoxin, complement c5 alpha' chain. Exotoxin 1. Chain: x, y. Synonym: ssl7. Engineered: yes.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: blood. Other_details: outdated plasma pools. Staphylococcus aureus subsp. Aureus. Organism_taxid: 282458. Strain: mrsa252. Expressed in: escherichia coli.

Resolution:

3.60Å R-factor: 0.201 R-free: 0.263

Authors:

N.S.Laursen,N.Gordon,S.Hermans,N.Lorenz,N.Jackson,B.Wines,E. J.B.Christensen,M.Jensen,F.Fredslund,M.Bjerre,L.Sottrup-Jen J.D.Fraser,G.R.Andersen

Key ref:

N.S.Laursen et al. (2010). Structural basis for inhibition of complement C5 by the SSL7 protein from Staphylococcus aureus. Proc Natl Acad Sci U S A, 107, 3681-3686. PubMed id: 20133685 DOI: 10.1073/pnas.0910565107

Date:

09-Nov-09 Release date: 24-Nov-09

Protein chain

P01031  (CO5_HUMAN) -  Complement C5

Seq: 1676 a.a.

Struc: 1622 a.a.*

Protein chains

Q6GJP2  (Q6GJP2_STAAR) -  Exotoxin 1

Seq: 231 a.a.

Struc: 191 a.a.

Protein chain

P01031  (CO5_HUMAN) -  Complement C5

Seq: 1676 a.a.

Struc: 1478 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Cellular component: extracellular region (2 terms)
• Biological process: inflammatory response (3 terms)
• Biochemical function: protein binding (2 terms)

DOI no: 10.1073/pnas.0910565107

Proc Natl Acad Sci U S A 107:3681-3686 (2010)

PubMed id: 20133685

Structural basis for inhibition of complement C5 by the SSL7 protein from Staphylococcus aureus.

N.S.Laursen, N.Gordon, S.Hermans, N.Lorenz, N.Jackson, B.Wines, E.Spillner, J.B.Christensen, M.Jensen, F.Fredslund, M.Bjerre, L.Sottrup-Jensen, J.D.Fraser, G.R.Andersen.

ABSTRACT

Staphylococcus aureus secretes the SSL7 protein as part of its immune evasion strategy. The protein binds both complement C5 and IgA, yet it is unclear whether SSL7 cross-links these two proteins and, if so, what purpose this serves the pathogen. We have isolated a stable IgA-SSL7-C5 complex, and our crystal structure of the C5-SSL7 complex confirms that binding to C5 occurs exclusively through the C-terminal beta-grasp domain of SSL7 leaving the OB domain free to interact with IgA. SSL7 interacts with C5 >70 A from the C5a cleavage site without inducing significant conformational changes in C5, and efficient inhibition of convertase cleavage of C5 is shown to be IgA dependent. Inhibition of C5a production and bacteriolysis are all shown to require C5 and IgA binding while inhibition of hemolysis is achieved by the C5 binding SSL7 beta-grasp domain alone. These results provide a conceptual and structural basis for the development of a highly specific complement inhibitor preventing only the formation of the lytic membrane attack complex without affecting the important signaling functions of C5a.

Selected figure(s)

Figure 2.
The C5-SSL7 interface. (A) Selected atomic interactions between C5 (gray carbon atoms, * after residue number) and SSL7 (green carbon atoms). Intermolecular hydrogen bonds and electrostatic interactions are shown with dotted lines. (B) Inhibition of sMAC formation in serum by SSL7. (C) Inhibition of hemolysis with recombinant full-length SSL7 from various S. aureus strains. The corresponding sequences are shown in Fig. S2.

Figure 3.
Consequences of SSL7 mutants defective in C5 and IgA binding on complement C5-mediated functions. (A and B) The ability of SSL7′ and SSL7′ mutants to inhibit the hemolytic activity in 20% human serum against human red blood cells (A) or 20% rabbit serum against human red blood cells (B). These assays were performed in triplicate and represent the results from a single representative donor. Equivalent results were achieved from multiple donors. (C) Inhibition by 1 μM SSL7′ and SSL7′ mutants against killing of E. coli by 5% human serum. Bacterial survival was enumerated by colony plating in triplicate for each dilution. Results are representative of three repeat experiments. (D) Inhibition by varying concentrations of SSL7′ and SSL7′ mutants of complement C5a production in response to the addition of 10^7 heat-killed S. aureus to 10% cell-free human serum. C5a was quantified by sandwich ELISA, using a commercial C5a as a concentration standard. The results are representative of two separate experiments from a single donor.

Figures were selected by the author.