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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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Crystal structure of apo-ClfB(197–542).A. Domain organization of ClfB. The numbers of the amino acid residues identifying the boundaries between adjacent domains are indicated below. S, signal sequence; N1-3, N-terminal fibrinogen binding region; R, serine-aspartate repeat region; W, wall-spanning domain; M, membrane anchor; C, cytoplasmic positively charged tail. The N2 and N3 domains were used in crystallization of the ClfB(197–542)-peptide complexes. B. Ribbon representation of the structure of apo-ClfB(197–542), with its N and C terminus indicated. The N2 and N3 domains are shown in orange and magenta, respectively. The strands and loops are marked. C. Ribbon representation of the two symmetry-related molecules in the unit cell, shown in orange and magenta, respectively. The N and C termini of both molecules are indicated. D. Closer view of the interaction between the two symmetry-related molecules. The N-terminus of one molecule (amino acids 196–201) is shown as sticks and the other one is colored in magenta as in (B). The amino acids from both molecules are marked in red and black characters, respectively. The hydrogen bonds are shown as red dashed lines.
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ppat-1002751-g001: Crystal structure of apo-ClfB(197–542).A. Domain organization of ClfB. The numbers of the amino acid residues identifying the boundaries between adjacent domains are indicated below. S, signal sequence; N1-3, N-terminal fibrinogen binding region; R, serine-aspartate repeat region; W, wall-spanning domain; M, membrane anchor; C, cytoplasmic positively charged tail. The N2 and N3 domains were used in crystallization of the ClfB(197–542)-peptide complexes. B. Ribbon representation of the structure of apo-ClfB(197–542), with its N and C terminus indicated. The N2 and N3 domains are shown in orange and magenta, respectively. The strands and loops are marked. C. Ribbon representation of the two symmetry-related molecules in the unit cell, shown in orange and magenta, respectively. The N and C termini of both molecules are indicated. D. Closer view of the interaction between the two symmetry-related molecules. The N-terminus of one molecule (amino acids 196–201) is shown as sticks and the other one is colored in magenta as in (B). The amino acids from both molecules are marked in red and black characters, respectively. The hydrogen bonds are shown as red dashed lines.

Mentions: Previous studies indicated that a segment of ClfB containing N2 and N3 regions (Figure 1A) is sufficient for recognition of Fg α and CK10 [18], [27], [29]. We therefore cloned the segment encoding the two regions (amino acids 197 to 542) of the ClfB protein from S. aureus and purified the protein from E. coli for our structural studies. The structure of the ClfB(208–540)-Fg α(316–328) complex was solved by a Se-Met derived protein and was used as a starting model for determination of the other structures by the molecular replacement method (Table 1).


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)

Crystal structure of apo-ClfB(197–542).A. Domain organization of ClfB. The numbers of the amino acid residues identifying the boundaries between adjacent domains are indicated below. S, signal sequence; N1-3, N-terminal fibrinogen binding region; R, serine-aspartate repeat region; W, wall-spanning domain; M, membrane anchor; C, cytoplasmic positively charged tail. The N2 and N3 domains were used in crystallization of the ClfB(197–542)-peptide complexes. B. Ribbon representation of the structure of apo-ClfB(197–542), with its N and C terminus indicated. The N2 and N3 domains are shown in orange and magenta, respectively. The strands and loops are marked. C. Ribbon representation of the two symmetry-related molecules in the unit cell, shown in orange and magenta, respectively. The N and C termini of both molecules are indicated. D. Closer view of the interaction between the two symmetry-related molecules. The N-terminus of one molecule (amino acids 196–201) is shown as sticks and the other one is colored in magenta as in (B). The amino acids from both molecules are marked in red and black characters, respectively. The hydrogen bonds are shown as red dashed lines.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1002751-g001: Crystal structure of apo-ClfB(197–542).A. Domain organization of ClfB. The numbers of the amino acid residues identifying the boundaries between adjacent domains are indicated below. S, signal sequence; N1-3, N-terminal fibrinogen binding region; R, serine-aspartate repeat region; W, wall-spanning domain; M, membrane anchor; C, cytoplasmic positively charged tail. The N2 and N3 domains were used in crystallization of the ClfB(197–542)-peptide complexes. B. Ribbon representation of the structure of apo-ClfB(197–542), with its N and C terminus indicated. The N2 and N3 domains are shown in orange and magenta, respectively. The strands and loops are marked. C. Ribbon representation of the two symmetry-related molecules in the unit cell, shown in orange and magenta, respectively. The N and C termini of both molecules are indicated. D. Closer view of the interaction between the two symmetry-related molecules. The N-terminus of one molecule (amino acids 196–201) is shown as sticks and the other one is colored in magenta as in (B). The amino acids from both molecules are marked in red and black characters, respectively. The hydrogen bonds are shown as red dashed lines.
Mentions: Previous studies indicated that a segment of ClfB containing N2 and N3 regions (Figure 1A) is sufficient for recognition of Fg α and CK10 [18], [27], [29]. We therefore cloned the segment encoding the two regions (amino acids 197 to 542) of the ClfB protein from S. aureus and purified the protein from E. coli for our structural studies. The structure of the ClfB(208–540)-Fg α(316–328) complex was solved by a Se-Met derived protein and was used as a starting model for determination of the other structures by the molecular replacement method (Table 1).

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