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Crystal structures reveal the multi-ligand binding mechanism of Staphylococcus aureus ClfB.

Xiang H, Feng Y, Wang J, Liu B, Chen Y, Liu L, Deng X, Yang M - PLoS Pathog. (2012)

Bottom Line: Structural comparison revealed a conserved glycine-serine-rich (GSR) ClfB binding motif (GSSGXGXXG) within the ligands, which was also found in other human proteins such as Engrailed protein, TCF20 and Dermokine proteins.The results presented here highlight the multi-ligand binding property of ClfB, which is very distinct from other characterized MSCRAMMs to-date.Our results provide a template for the identification of other molecules targeted by S. aureus during its colonization and infection.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Protein Sciences of Ministry of Education, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
Staphylococcus aureus (S. aureus) pathogenesis is a complex process involving a diverse array of extracellular and cell wall components. ClfB, an MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules) family surface protein, described as a fibrinogen-binding clumping factor, is a key determinant of S. aureus nasal colonization, but the molecular basis for ClfB-ligand recognition remains unknown. In this study, we solved the crystal structures of apo-ClfB and its complexes with fibrinogen α (Fg α) and cytokeratin 10 (CK10) peptides. Structural comparison revealed a conserved glycine-serine-rich (GSR) ClfB binding motif (GSSGXGXXG) within the ligands, which was also found in other human proteins such as Engrailed protein, TCF20 and Dermokine proteins. Interaction between Dermokine and ClfB was confirmed by subsequent binding assays. The crystal structure of ClfB complexed with a 15-residue peptide derived from Dermokine revealed the same peptide binding mode of ClfB as identified in the crystal structures of ClfB-Fg α and ClfB-CK10. The results presented here highlight the multi-ligand binding property of ClfB, which is very distinct from other characterized MSCRAMMs to-date. The adherence of multiple peptides carrying the GSR motif into the same pocket in ClfB is reminiscent of MHC molecules. Our results provide a template for the identification of other molecules targeted by S. aureus during its colonization and infection. We propose that other MSCRAMMs like ClfA and SdrG also possess multi-ligand binding properties.

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Structural aligment of ClfB, ClfA and SdrG.A. Sequence aligment of ClfB (amino acids 212–550), ClfA (amino acids 229–544) and SdrG (amino acids 117–441). Residues displaying 100% and 50% identity are shown in dark blue and light blue, respectively. F406 in ClfB is marked by red star. B. Ribbon representation of ClfB, with conserved residues colored from red to green following the order from highly conserved to less conserved. C. Superimposition of apo-ClfB and apo-SdrG, colored in orange and cyan, respectively. D. Superimposition of ClfB-Fg α, SdrG-Fg β and ClfA-Fg γ complexes. The SdrG-Fg β and ClfB-Fg α are colored as in Figure 3C. The ClfA-Fg γ complex is colored in blue.
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ppat-1002751-g003: Structural aligment of ClfB, ClfA and SdrG.A. Sequence aligment of ClfB (amino acids 212–550), ClfA (amino acids 229–544) and SdrG (amino acids 117–441). Residues displaying 100% and 50% identity are shown in dark blue and light blue, respectively. F406 in ClfB is marked by red star. B. Ribbon representation of ClfB, with conserved residues colored from red to green following the order from highly conserved to less conserved. C. Superimposition of apo-ClfB and apo-SdrG, colored in orange and cyan, respectively. D. Superimposition of ClfB-Fg α, SdrG-Fg β and ClfA-Fg γ complexes. The SdrG-Fg β and ClfB-Fg α are colored as in Figure 3C. The ClfA-Fg γ complex is colored in blue.

Mentions: In spite of the low identities in the amino acid sequences, the structures of ClfB, ClfA and SdrG exhibit high similarities (Figure 3). The most conserved residues are mainly located in the loop region of them (Figure 3B). Although the adherence domain organizations of ClfB, ClfA and SdrG and their ligand binding sites are conserved, the ligand binding specificities of the three MSCRAMMSs vary (Figure 3D) [18], [21], [28]. All the bound peptides form into a β-strand paired with the G-strand and pass through the tunnel formed by the N2, N3 and the end of the G-strand (Figure S3). In the ClfB-Fg α(316–328)/CK10(499–512) structures, one peptide is bound to one ClfB, in the same orientation as the Fg γ-chain peptide in ClfA and a reverse orientation compared to the Fg β-chain peptide in SdrG (Figure 3D) [21], [28].


Crystal structures reveal the multi-ligand binding mechanism of Staphylococcus aureus ClfB.

Xiang H, Feng Y, Wang J, Liu B, Chen Y, Liu L, Deng X, Yang M - PLoS Pathog. (2012)

Structural aligment of ClfB, ClfA and SdrG.A. Sequence aligment of ClfB (amino acids 212–550), ClfA (amino acids 229–544) and SdrG (amino acids 117–441). Residues displaying 100% and 50% identity are shown in dark blue and light blue, respectively. F406 in ClfB is marked by red star. B. Ribbon representation of ClfB, with conserved residues colored from red to green following the order from highly conserved to less conserved. C. Superimposition of apo-ClfB and apo-SdrG, colored in orange and cyan, respectively. D. Superimposition of ClfB-Fg α, SdrG-Fg β and ClfA-Fg γ complexes. The SdrG-Fg β and ClfB-Fg α are colored as in Figure 3C. The ClfA-Fg γ complex is colored in blue.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375286&req=5

ppat-1002751-g003: Structural aligment of ClfB, ClfA and SdrG.A. Sequence aligment of ClfB (amino acids 212–550), ClfA (amino acids 229–544) and SdrG (amino acids 117–441). Residues displaying 100% and 50% identity are shown in dark blue and light blue, respectively. F406 in ClfB is marked by red star. B. Ribbon representation of ClfB, with conserved residues colored from red to green following the order from highly conserved to less conserved. C. Superimposition of apo-ClfB and apo-SdrG, colored in orange and cyan, respectively. D. Superimposition of ClfB-Fg α, SdrG-Fg β and ClfA-Fg γ complexes. The SdrG-Fg β and ClfB-Fg α are colored as in Figure 3C. The ClfA-Fg γ complex is colored in blue.
Mentions: In spite of the low identities in the amino acid sequences, the structures of ClfB, ClfA and SdrG exhibit high similarities (Figure 3). The most conserved residues are mainly located in the loop region of them (Figure 3B). Although the adherence domain organizations of ClfB, ClfA and SdrG and their ligand binding sites are conserved, the ligand binding specificities of the three MSCRAMMSs vary (Figure 3D) [18], [21], [28]. All the bound peptides form into a β-strand paired with the G-strand and pass through the tunnel formed by the N2, N3 and the end of the G-strand (Figure S3). In the ClfB-Fg α(316–328)/CK10(499–512) structures, one peptide is bound to one ClfB, in the same orientation as the Fg γ-chain peptide in ClfA and a reverse orientation compared to the Fg β-chain peptide in SdrG (Figure 3D) [21], [28].

Bottom Line: Structural comparison revealed a conserved glycine-serine-rich (GSR) ClfB binding motif (GSSGXGXXG) within the ligands, which was also found in other human proteins such as Engrailed protein, TCF20 and Dermokine proteins.The results presented here highlight the multi-ligand binding property of ClfB, which is very distinct from other characterized MSCRAMMs to-date.Our results provide a template for the identification of other molecules targeted by S. aureus during its colonization and infection.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Protein Sciences of Ministry of Education, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
Staphylococcus aureus (S. aureus) pathogenesis is a complex process involving a diverse array of extracellular and cell wall components. ClfB, an MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules) family surface protein, described as a fibrinogen-binding clumping factor, is a key determinant of S. aureus nasal colonization, but the molecular basis for ClfB-ligand recognition remains unknown. In this study, we solved the crystal structures of apo-ClfB and its complexes with fibrinogen α (Fg α) and cytokeratin 10 (CK10) peptides. Structural comparison revealed a conserved glycine-serine-rich (GSR) ClfB binding motif (GSSGXGXXG) within the ligands, which was also found in other human proteins such as Engrailed protein, TCF20 and Dermokine proteins. Interaction between Dermokine and ClfB was confirmed by subsequent binding assays. The crystal structure of ClfB complexed with a 15-residue peptide derived from Dermokine revealed the same peptide binding mode of ClfB as identified in the crystal structures of ClfB-Fg α and ClfB-CK10. The results presented here highlight the multi-ligand binding property of ClfB, which is very distinct from other characterized MSCRAMMs to-date. The adherence of multiple peptides carrying the GSR motif into the same pocket in ClfB is reminiscent of MHC molecules. Our results provide a template for the identification of other molecules targeted by S. aureus during its colonization and infection. We propose that other MSCRAMMs like ClfA and SdrG also possess multi-ligand binding properties.

Show MeSH
Related in: MedlinePlus