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Stability of the octameric structure affects plasminogen-binding capacity of streptococcal enolase.

Cork AJ, Ericsson DJ, Law RH, Casey LW, Valkov E, Bertozzi C, Stamp A, Jovcevski B, Aquilina JA, Whisstock JC, Walker MJ, Kobe B - PLoS ONE (2015)

Bottom Line: The plasminogen binding ability of SENK312A and SENK362A is ~2- and ~3.4-fold greater than for the wild-type protein.A combination of thermal stability assays, native mass spectrometry and X-ray crystallography approaches shows that increased plasminogen binding ability correlates with decreased stability of the octamer.We propose that decreased stability of the octameric structure facilitates the access of plasmin(ogen) to its binding sites, leading to more efficient plasmin(ogen) binding and activation.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry and Molecular Biosciences and Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, 4072, Australia; Australian Infectious Disease Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia.

ABSTRACT
Group A Streptococcus (GAS) is a human pathogen that has the potential to cause invasive disease by binding and activating human plasmin(ogen). Streptococcal surface enolase (SEN) is an octameric α-enolase that is localized at the GAS cell surface. In addition to its glycolytic role inside the cell, SEN functions as a receptor for plasmin(ogen) on the bacterial surface, but the understanding of the molecular basis of plasmin(ogen) binding is limited. In this study, we determined the crystal and solution structures of GAS SEN and characterized the increased plasminogen binding by two SEN mutants. The plasminogen binding ability of SENK312A and SENK362A is ~2- and ~3.4-fold greater than for the wild-type protein. A combination of thermal stability assays, native mass spectrometry and X-ray crystallography approaches shows that increased plasminogen binding ability correlates with decreased stability of the octamer. We propose that decreased stability of the octameric structure facilitates the access of plasmin(ogen) to its binding sites, leading to more efficient plasmin(ogen) binding and activation.

No MeSH data available.


Related in: MedlinePlus

Small-angle X-ray scattering (SAXS) data.(A) Pairwise interatomic distance distribution derived from SAXS. The maximum distance (Dmax) from the P(r) is 157 Å, and the radius of gyration (Rg) is 50.6 Å. (B) Experimental scattering of wild-type SEN on absolute, logarithmic scale, with 1σ error bars shown in gray. Theoretical fits of the ab initio models (Fig. 1C) are shown in blue for the dummy residue model, and purple for the cluster-representative bead model. (C) Guinier transformation of the data from a concentration series, demonstrating concentration-dependent Rg variation of < 5% and linearity over the region q.Rg < 1.3.
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pone.0121764.g002: Small-angle X-ray scattering (SAXS) data.(A) Pairwise interatomic distance distribution derived from SAXS. The maximum distance (Dmax) from the P(r) is 157 Å, and the radius of gyration (Rg) is 50.6 Å. (B) Experimental scattering of wild-type SEN on absolute, logarithmic scale, with 1σ error bars shown in gray. Theoretical fits of the ab initio models (Fig. 1C) are shown in blue for the dummy residue model, and purple for the cluster-representative bead model. (C) Guinier transformation of the data from a concentration series, demonstrating concentration-dependent Rg variation of < 5% and linearity over the region q.Rg < 1.3.

Mentions: In solution, GAS SEN exists as an octamer [17]. In the crystals, the octamer is made up of a tetramer of homo-dimers and consists of two types of interfaces. Dimerization of two enolase molecules involves the ‘major interface’, whereas octamerization occurs through the ‘minor interface’ (Fig. 1B). Each major and minor interface buries a total surface area of 3648 Å2 and 2580 Å2, respectively (calculated by PISA [49]), with the octamer having an approximate diameter of 153 Å and thickness of 54 Å. A particle of this size is also consistent with small-angle X-ray scattering (SAXS) data, from which we identified a maximum particle dimension of 157 Å (Fig. 2A), and a volume-derived molecular weight of 369.4 kDa. Furthermore, SAXS-based ab initio modeling restrained by four-fold rotational symmetry was able to restore shapes consistent with the crystal structure (Fig. 1C and Fig. 2B). BS1 is located in the minor inter-subunit interface.


Stability of the octameric structure affects plasminogen-binding capacity of streptococcal enolase.

Cork AJ, Ericsson DJ, Law RH, Casey LW, Valkov E, Bertozzi C, Stamp A, Jovcevski B, Aquilina JA, Whisstock JC, Walker MJ, Kobe B - PLoS ONE (2015)

Small-angle X-ray scattering (SAXS) data.(A) Pairwise interatomic distance distribution derived from SAXS. The maximum distance (Dmax) from the P(r) is 157 Å, and the radius of gyration (Rg) is 50.6 Å. (B) Experimental scattering of wild-type SEN on absolute, logarithmic scale, with 1σ error bars shown in gray. Theoretical fits of the ab initio models (Fig. 1C) are shown in blue for the dummy residue model, and purple for the cluster-representative bead model. (C) Guinier transformation of the data from a concentration series, demonstrating concentration-dependent Rg variation of < 5% and linearity over the region q.Rg < 1.3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373793&req=5

pone.0121764.g002: Small-angle X-ray scattering (SAXS) data.(A) Pairwise interatomic distance distribution derived from SAXS. The maximum distance (Dmax) from the P(r) is 157 Å, and the radius of gyration (Rg) is 50.6 Å. (B) Experimental scattering of wild-type SEN on absolute, logarithmic scale, with 1σ error bars shown in gray. Theoretical fits of the ab initio models (Fig. 1C) are shown in blue for the dummy residue model, and purple for the cluster-representative bead model. (C) Guinier transformation of the data from a concentration series, demonstrating concentration-dependent Rg variation of < 5% and linearity over the region q.Rg < 1.3.
Mentions: In solution, GAS SEN exists as an octamer [17]. In the crystals, the octamer is made up of a tetramer of homo-dimers and consists of two types of interfaces. Dimerization of two enolase molecules involves the ‘major interface’, whereas octamerization occurs through the ‘minor interface’ (Fig. 1B). Each major and minor interface buries a total surface area of 3648 Å2 and 2580 Å2, respectively (calculated by PISA [49]), with the octamer having an approximate diameter of 153 Å and thickness of 54 Å. A particle of this size is also consistent with small-angle X-ray scattering (SAXS) data, from which we identified a maximum particle dimension of 157 Å (Fig. 2A), and a volume-derived molecular weight of 369.4 kDa. Furthermore, SAXS-based ab initio modeling restrained by four-fold rotational symmetry was able to restore shapes consistent with the crystal structure (Fig. 1C and Fig. 2B). BS1 is located in the minor inter-subunit interface.

Bottom Line: The plasminogen binding ability of SENK312A and SENK362A is ~2- and ~3.4-fold greater than for the wild-type protein.A combination of thermal stability assays, native mass spectrometry and X-ray crystallography approaches shows that increased plasminogen binding ability correlates with decreased stability of the octamer.We propose that decreased stability of the octameric structure facilitates the access of plasmin(ogen) to its binding sites, leading to more efficient plasmin(ogen) binding and activation.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry and Molecular Biosciences and Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, 4072, Australia; Australian Infectious Disease Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia.

ABSTRACT
Group A Streptococcus (GAS) is a human pathogen that has the potential to cause invasive disease by binding and activating human plasmin(ogen). Streptococcal surface enolase (SEN) is an octameric α-enolase that is localized at the GAS cell surface. In addition to its glycolytic role inside the cell, SEN functions as a receptor for plasmin(ogen) on the bacterial surface, but the understanding of the molecular basis of plasmin(ogen) binding is limited. In this study, we determined the crystal and solution structures of GAS SEN and characterized the increased plasminogen binding by two SEN mutants. The plasminogen binding ability of SENK312A and SENK362A is ~2- and ~3.4-fold greater than for the wild-type protein. A combination of thermal stability assays, native mass spectrometry and X-ray crystallography approaches shows that increased plasminogen binding ability correlates with decreased stability of the octamer. We propose that decreased stability of the octameric structure facilitates the access of plasmin(ogen) to its binding sites, leading to more efficient plasmin(ogen) binding and activation.

No MeSH data available.


Related in: MedlinePlus