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Secreted proteases control autolysin-mediated biofilm growth of Staphylococcus aureus.

Chen C, Krishnan V, Macon K, Manne K, Narayana SV, Schneewind O - J. Biol. Chem. (2013)

Bottom Line: Blocking S. aureus colonization may reduce the incidence of invasive infectious diseases; however, the mechanism whereby Esp disrupts biofilms is unknown.Both atl and sspA are necessary for biofilm formation, and purified SspA cleaves Atl-derived murein hydrolases.Thus, S. aureus biofilms are formed via the controlled secretion and proteolysis of autolysin, and this developmental program appears to be perturbed by the Esp protease of S. epidermidis.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Microbiology, University of Chicago, Chicago, Illinois 60637.

ABSTRACT
Staphylococcus epidermidis, a commensal of humans, secretes Esp protease to prevent Staphylococcus aureus biofilm formation and colonization. Blocking S. aureus colonization may reduce the incidence of invasive infectious diseases; however, the mechanism whereby Esp disrupts biofilms is unknown. We show here that Esp cleaves autolysin (Atl)-derived murein hydrolases and prevents staphylococcal release of DNA, which serves as extracellular matrix in biofilms. The three-dimensional structure of Esp was revealed by x-ray crystallography and shown to be highly similar to that of S. aureus V8 (SspA). Both atl and sspA are necessary for biofilm formation, and purified SspA cleaves Atl-derived murein hydrolases. Thus, S. aureus biofilms are formed via the controlled secretion and proteolysis of autolysin, and this developmental program appears to be perturbed by the Esp protease of S. epidermidis.

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Comparison between Esp and V8 crystal structures.a, ribbon representation of the refined crystal structure of active Esp. The α-helices are represented in cyan, β-strands are in magenta, and loop regions are in light brown. The putative catalytic His117, Asp159, and Ser235 residue side chains are represented as green sticks. b, superposition of Esp (PDB code 4JCN, represented in magenta) and pancreatic trypsin (PDB code 1TRM, in cyan) crystal structures. Surface loops (A, C, D, 1, 2, and 3) that dictate substrate specificity for trypsin are labeled, and the disulfide bonds (in yellow) that hold its structure together are also shown. c, superposition of Esp (magenta) and V8 (ivory, PDB code 1QY6) crystal structures. d, significant residue differences observed between Esp (magenta) and V8 (ivory) crystal structures are shown in their respective positions. Side chains are shown as sticks: green for V8 and magenta for Esp residues.
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Figure 8: Comparison between Esp and V8 crystal structures.a, ribbon representation of the refined crystal structure of active Esp. The α-helices are represented in cyan, β-strands are in magenta, and loop regions are in light brown. The putative catalytic His117, Asp159, and Ser235 residue side chains are represented as green sticks. b, superposition of Esp (PDB code 4JCN, represented in magenta) and pancreatic trypsin (PDB code 1TRM, in cyan) crystal structures. Surface loops (A, C, D, 1, 2, and 3) that dictate substrate specificity for trypsin are labeled, and the disulfide bonds (in yellow) that hold its structure together are also shown. c, superposition of Esp (magenta) and V8 (ivory, PDB code 1QY6) crystal structures. d, significant residue differences observed between Esp (magenta) and V8 (ivory) crystal structures are shown in their respective positions. Side chains are shown as sticks: green for V8 and magenta for Esp residues.

Mentions: Purified Esp was crystallized, and its three-dimensional structure was determined using x-ray crystallography. Esp displays a β-barrel fold assembled from two discrete domains and a C-terminal α-helix, similar to eukaryotic serine proteases of the chymotrypsin family (Fig. 8, a and b) (53–55). Even though Esp exhibits a highly conserved, compact β-barrel fold, the five or more intradomain disulfide bonds that are responsible for the structural rigidity of eukaryotic serine proteases are absent (54). Each of the two Esp domains is comprised of six antiparallel β-strands, and the solvent-accessible catalytic and substrate binding sites are situated at the interface of the two domains. The N-terminal domain (chymotrypsin nomenclature) is comprised primarily of residues Gln77–Ile183, whereas the C-terminal domain encompasses Ser184–Ile264. Although the position of the C-terminal α-helix (Asn266–Ile276) is conserved with that of other serine proteases, the N-terminal segment (Val67–Gln76) contains a short β-strand that is associated with the substrate-binding S1 pocket and distinct from eukaryotic serine proteases (Fig. 8b). In addition to the conserved position of putative catalytic triad residues (Ser235, Asp159, and His117), the substrate-binding region (S1 pocket) and the oxyanion hole, which together constitute the critical functional elements of activated serine proteases, are also conserved in Esp (Fig. 8a). A search for structural homologues of Esp identified S. aureus V8, a serine protease with a Z-score of 39.7 and 59% primary sequence identity (PDB code 1QY6) (33).


Secreted proteases control autolysin-mediated biofilm growth of Staphylococcus aureus.

Chen C, Krishnan V, Macon K, Manne K, Narayana SV, Schneewind O - J. Biol. Chem. (2013)

Comparison between Esp and V8 crystal structures.a, ribbon representation of the refined crystal structure of active Esp. The α-helices are represented in cyan, β-strands are in magenta, and loop regions are in light brown. The putative catalytic His117, Asp159, and Ser235 residue side chains are represented as green sticks. b, superposition of Esp (PDB code 4JCN, represented in magenta) and pancreatic trypsin (PDB code 1TRM, in cyan) crystal structures. Surface loops (A, C, D, 1, 2, and 3) that dictate substrate specificity for trypsin are labeled, and the disulfide bonds (in yellow) that hold its structure together are also shown. c, superposition of Esp (magenta) and V8 (ivory, PDB code 1QY6) crystal structures. d, significant residue differences observed between Esp (magenta) and V8 (ivory) crystal structures are shown in their respective positions. Side chains are shown as sticks: green for V8 and magenta for Esp residues.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 8: Comparison between Esp and V8 crystal structures.a, ribbon representation of the refined crystal structure of active Esp. The α-helices are represented in cyan, β-strands are in magenta, and loop regions are in light brown. The putative catalytic His117, Asp159, and Ser235 residue side chains are represented as green sticks. b, superposition of Esp (PDB code 4JCN, represented in magenta) and pancreatic trypsin (PDB code 1TRM, in cyan) crystal structures. Surface loops (A, C, D, 1, 2, and 3) that dictate substrate specificity for trypsin are labeled, and the disulfide bonds (in yellow) that hold its structure together are also shown. c, superposition of Esp (magenta) and V8 (ivory, PDB code 1QY6) crystal structures. d, significant residue differences observed between Esp (magenta) and V8 (ivory) crystal structures are shown in their respective positions. Side chains are shown as sticks: green for V8 and magenta for Esp residues.
Mentions: Purified Esp was crystallized, and its three-dimensional structure was determined using x-ray crystallography. Esp displays a β-barrel fold assembled from two discrete domains and a C-terminal α-helix, similar to eukaryotic serine proteases of the chymotrypsin family (Fig. 8, a and b) (53–55). Even though Esp exhibits a highly conserved, compact β-barrel fold, the five or more intradomain disulfide bonds that are responsible for the structural rigidity of eukaryotic serine proteases are absent (54). Each of the two Esp domains is comprised of six antiparallel β-strands, and the solvent-accessible catalytic and substrate binding sites are situated at the interface of the two domains. The N-terminal domain (chymotrypsin nomenclature) is comprised primarily of residues Gln77–Ile183, whereas the C-terminal domain encompasses Ser184–Ile264. Although the position of the C-terminal α-helix (Asn266–Ile276) is conserved with that of other serine proteases, the N-terminal segment (Val67–Gln76) contains a short β-strand that is associated with the substrate-binding S1 pocket and distinct from eukaryotic serine proteases (Fig. 8b). In addition to the conserved position of putative catalytic triad residues (Ser235, Asp159, and His117), the substrate-binding region (S1 pocket) and the oxyanion hole, which together constitute the critical functional elements of activated serine proteases, are also conserved in Esp (Fig. 8a). A search for structural homologues of Esp identified S. aureus V8, a serine protease with a Z-score of 39.7 and 59% primary sequence identity (PDB code 1QY6) (33).

Bottom Line: Blocking S. aureus colonization may reduce the incidence of invasive infectious diseases; however, the mechanism whereby Esp disrupts biofilms is unknown.Both atl and sspA are necessary for biofilm formation, and purified SspA cleaves Atl-derived murein hydrolases.Thus, S. aureus biofilms are formed via the controlled secretion and proteolysis of autolysin, and this developmental program appears to be perturbed by the Esp protease of S. epidermidis.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Microbiology, University of Chicago, Chicago, Illinois 60637.

ABSTRACT
Staphylococcus epidermidis, a commensal of humans, secretes Esp protease to prevent Staphylococcus aureus biofilm formation and colonization. Blocking S. aureus colonization may reduce the incidence of invasive infectious diseases; however, the mechanism whereby Esp disrupts biofilms is unknown. We show here that Esp cleaves autolysin (Atl)-derived murein hydrolases and prevents staphylococcal release of DNA, which serves as extracellular matrix in biofilms. The three-dimensional structure of Esp was revealed by x-ray crystallography and shown to be highly similar to that of S. aureus V8 (SspA). Both atl and sspA are necessary for biofilm formation, and purified SspA cleaves Atl-derived murein hydrolases. Thus, S. aureus biofilms are formed via the controlled secretion and proteolysis of autolysin, and this developmental program appears to be perturbed by the Esp protease of S. epidermidis.

Show MeSH
Related in: MedlinePlus