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Flexible Structure of Peptide-Bound Filamin A Mechanosensor Domain Pair 20-21.

Seppälä J, Tossavainen H, Rodic N, Permi P, Pentikäinen U, Ylänne J - PLoS ONE (2015)

Bottom Line: The atomic structures of these mechanosensor domain pairs in the resting state are known, as well as the structures of individual IgFLN21 with ligand peptides.Here, using small-angle x-ray scattering-based modelling, x-ray crystallography, and NMR, we show that the adaptor protein migfilin-derived peptide-bound structure of IgFLNa20-21 is flexible and adopts distinctive conformations depending on the presence or absence of the interacting peptide.The conformational changes reported here may be common for all peptides and may play a role in the mechanosensor function of the site.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.

ABSTRACT
Filamins (FLNs) are large, multidomain actin cross-linking proteins with diverse functions. Besides regulating the actin cytoskeleton, they serve as important links between the extracellular matrix and the cytoskeleton by binding cell surface receptors, functioning as scaffolds for signaling proteins, and binding several other cytoskeletal proteins that regulate cell adhesion dynamics. Structurally, FLNs are formed of an amino terminal actin-binding domain followed by 24 immunoglobulin-like domains (IgFLNs). Recent studies have demonstrated that myosin-mediated contractile forces can reveal hidden protein binding sites in the domain pairs IgFLNa18-19 and 20-21, enabling FLNs to transduce mechanical signals in cells. The atomic structures of these mechanosensor domain pairs in the resting state are known, as well as the structures of individual IgFLN21 with ligand peptides. However, little experimental data is available on how interacting protein binding deforms the domain pair structures. Here, using small-angle x-ray scattering-based modelling, x-ray crystallography, and NMR, we show that the adaptor protein migfilin-derived peptide-bound structure of IgFLNa20-21 is flexible and adopts distinctive conformations depending on the presence or absence of the interacting peptide. The conformational changes reported here may be common for all peptides and may play a role in the mechanosensor function of the site.

No MeSH data available.


Related in: MedlinePlus

EOM modelling of migfilin peptide binding on IgFLNa(∆A)20–21.Left panels, Fit from the selected ensemble of conformers to the experimental scattering. Radius of gyration, Rg (middle panels), and particle maximum dimension, Dmax (right panels), distribution histograms of the selected conformers versus the pool. Also shown in the right panel are examples of rigid body models of the selected conformers corresponding to the histogram peaks.
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pone.0136969.g003: EOM modelling of migfilin peptide binding on IgFLNa(∆A)20–21.Left panels, Fit from the selected ensemble of conformers to the experimental scattering. Radius of gyration, Rg (middle panels), and particle maximum dimension, Dmax (right panels), distribution histograms of the selected conformers versus the pool. Also shown in the right panel are examples of rigid body models of the selected conformers corresponding to the histogram peaks.

Mentions: Kratky and Porod–Debye plots showed that the peptide-bound IgFLNa20–21 and IgFLNaΔA20–21 with or without peptide are flexible. Thus, traditional ab initio and rigid-body modeling techniques are not suitable for such particles with multiple conformations. Therefore, EOM analysis of the SAXS data was used to further model the conformational space of the two-domain fragments with and without peptide (Fig 3). Based on the EOM analysis, IgFLNa20–21 is mainly in a compact conformation with average Rg and Dmax of 2.0 nm and 6.6 nm, respectively (Fig 3). Rg and Dmax values are very similar to those obtained from the Guinier plots and P(r) function, and a similar Dmax value can also be measured from the crystal structure of IgFLNa20–21. Interestingly, EOM-selected conformations also included a minor population of extended conformations with peaks in Rg and Dmax around 2.8 nm and 8.5 nm, respectively. This explains the moderate fit of the IgFLNa20–21 crystal structure to the scattering data, as the scattering computed from the structure only represents the compact conformation (see above). Migfilin peptide-binding to IgFLNa20–21 changed the shape of the size distribution of the EOM-selected population compared to the non-bound one. With bound peptide, the size distribution of selected conformations is wide, with an average Rg and Dmax of 2.3 nm and 7.5 nm, respectively (Fig 3). Accordingly, peptide binding to IgFLNa20–21 opens the compact two-domain fragment, also making it simultaneously more flexible, as the size distribution covers a wider range than without peptide.


Flexible Structure of Peptide-Bound Filamin A Mechanosensor Domain Pair 20-21.

Seppälä J, Tossavainen H, Rodic N, Permi P, Pentikäinen U, Ylänne J - PLoS ONE (2015)

EOM modelling of migfilin peptide binding on IgFLNa(∆A)20–21.Left panels, Fit from the selected ensemble of conformers to the experimental scattering. Radius of gyration, Rg (middle panels), and particle maximum dimension, Dmax (right panels), distribution histograms of the selected conformers versus the pool. Also shown in the right panel are examples of rigid body models of the selected conformers corresponding to the histogram peaks.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554727&req=5

pone.0136969.g003: EOM modelling of migfilin peptide binding on IgFLNa(∆A)20–21.Left panels, Fit from the selected ensemble of conformers to the experimental scattering. Radius of gyration, Rg (middle panels), and particle maximum dimension, Dmax (right panels), distribution histograms of the selected conformers versus the pool. Also shown in the right panel are examples of rigid body models of the selected conformers corresponding to the histogram peaks.
Mentions: Kratky and Porod–Debye plots showed that the peptide-bound IgFLNa20–21 and IgFLNaΔA20–21 with or without peptide are flexible. Thus, traditional ab initio and rigid-body modeling techniques are not suitable for such particles with multiple conformations. Therefore, EOM analysis of the SAXS data was used to further model the conformational space of the two-domain fragments with and without peptide (Fig 3). Based on the EOM analysis, IgFLNa20–21 is mainly in a compact conformation with average Rg and Dmax of 2.0 nm and 6.6 nm, respectively (Fig 3). Rg and Dmax values are very similar to those obtained from the Guinier plots and P(r) function, and a similar Dmax value can also be measured from the crystal structure of IgFLNa20–21. Interestingly, EOM-selected conformations also included a minor population of extended conformations with peaks in Rg and Dmax around 2.8 nm and 8.5 nm, respectively. This explains the moderate fit of the IgFLNa20–21 crystal structure to the scattering data, as the scattering computed from the structure only represents the compact conformation (see above). Migfilin peptide-binding to IgFLNa20–21 changed the shape of the size distribution of the EOM-selected population compared to the non-bound one. With bound peptide, the size distribution of selected conformations is wide, with an average Rg and Dmax of 2.3 nm and 7.5 nm, respectively (Fig 3). Accordingly, peptide binding to IgFLNa20–21 opens the compact two-domain fragment, also making it simultaneously more flexible, as the size distribution covers a wider range than without peptide.

Bottom Line: The atomic structures of these mechanosensor domain pairs in the resting state are known, as well as the structures of individual IgFLN21 with ligand peptides.Here, using small-angle x-ray scattering-based modelling, x-ray crystallography, and NMR, we show that the adaptor protein migfilin-derived peptide-bound structure of IgFLNa20-21 is flexible and adopts distinctive conformations depending on the presence or absence of the interacting peptide.The conformational changes reported here may be common for all peptides and may play a role in the mechanosensor function of the site.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.

ABSTRACT
Filamins (FLNs) are large, multidomain actin cross-linking proteins with diverse functions. Besides regulating the actin cytoskeleton, they serve as important links between the extracellular matrix and the cytoskeleton by binding cell surface receptors, functioning as scaffolds for signaling proteins, and binding several other cytoskeletal proteins that regulate cell adhesion dynamics. Structurally, FLNs are formed of an amino terminal actin-binding domain followed by 24 immunoglobulin-like domains (IgFLNs). Recent studies have demonstrated that myosin-mediated contractile forces can reveal hidden protein binding sites in the domain pairs IgFLNa18-19 and 20-21, enabling FLNs to transduce mechanical signals in cells. The atomic structures of these mechanosensor domain pairs in the resting state are known, as well as the structures of individual IgFLN21 with ligand peptides. However, little experimental data is available on how interacting protein binding deforms the domain pair structures. Here, using small-angle x-ray scattering-based modelling, x-ray crystallography, and NMR, we show that the adaptor protein migfilin-derived peptide-bound structure of IgFLNa20-21 is flexible and adopts distinctive conformations depending on the presence or absence of the interacting peptide. The conformational changes reported here may be common for all peptides and may play a role in the mechanosensor function of the site.

No MeSH data available.


Related in: MedlinePlus