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Structure of the S100A4/myosin-IIA complex.

Ramagopal UA, Dulyaninova NG, Varney KM, Wilder PT, Nallamsetty S, Brenowitz M, Weber DJ, Almo SC, Bresnick AR - BMC Struct. Biol. (2013)

Bottom Line: This asymmetric binding mode was confirmed in NMR studies using a spin-labeled myosin-IIA peptide.These structural studies support the idea that residues 1908-1923 of the myosin-IIA chain heavy represent a core sequence for the S100A4/myosin-IIA complex.In addition, biophysical studies suggest that structural fluctuations within the myosin-IIA coiled-coil may facilitate S100A4 docking onto a single myosin-IIA polypeptide chain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. anne.bresnick@einstein.yu.edu.

ABSTRACT

Background: S100A4, a member of the S100 family of Ca2+-binding proteins, modulates the motility of both non-transformed and cancer cells by regulating the localization and stability of cellular protrusions. Biochemical studies have demonstrated that S100A4 binds to the C-terminal end of the myosin-IIA heavy chain coiled-coil and disassembles myosin-IIA filaments; however, the mechanism by which S100A4 mediates myosin-IIA depolymerization is not well understood.

Results: We determined the X-ray crystal structure of the S100A4Δ8C/MIIA(1908-1923) peptide complex, which showed an asymmetric binding mode for the myosin-IIA peptide across the S100A4 dimer interface. This asymmetric binding mode was confirmed in NMR studies using a spin-labeled myosin-IIA peptide. In addition, our NMR data indicate that S100A4Δ8C binds the MIIA(1908-1923) peptide in an orientation very similar to that observed for wild-type S100A4. Studies of complex formation using a longer, dimeric myosin-IIA construct demonstrated that S100A4 binding dissociates the two myosin-IIA polypeptide chains to form a complex composed of one S100A4 dimer and a single myosin-IIA polypeptide chain. This interaction is mediated, in part, by the instability of the region of the myosin-IIA coiled-coil encompassing the S100A4 binding site.

Conclusion: The structure of the S100A4/MIIA(1908-1923) peptide complex has revealed the overall architecture of this assembly and the detailed atomic interactions that mediate S100A4 binding to the myosin-IIA heavy chain. These structural studies support the idea that residues 1908-1923 of the myosin-IIA chain heavy represent a core sequence for the S100A4/myosin-IIA complex. In addition, biophysical studies suggest that structural fluctuations within the myosin-IIA coiled-coil may facilitate S100A4 docking onto a single myosin-IIA polypeptide chain.

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Interactions within the S100A4Δ8C/MIIA1908-1923 complex. Binding of the MIIA1908-1923 peptide (blue) to the S100A4Δ8C dimer involves direct electrostatic interactions (A) and water mediated electrostatic interactions (not shown) as well as hydrophobic interactions (B). Hydrogen bonds are shown as red dotted lines.
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Figure 5: Interactions within the S100A4Δ8C/MIIA1908-1923 complex. Binding of the MIIA1908-1923 peptide (blue) to the S100A4Δ8C dimer involves direct electrostatic interactions (A) and water mediated electrostatic interactions (not shown) as well as hydrophobic interactions (B). Hydrogen bonds are shown as red dotted lines.

Mentions: The 1.54 Å structure of the S100A4/MIIA1908-1923 complex revealed a single MIIA1908-1923 peptide binding across the S100A4 dimer interface (Figure 4A). Electron density was observed only for residues Asp1908-Leu1921 of the MIIA1908-1923 peptide. As shown in Figure 5A, there is an extensive H-bond network between myosin-IIA residues Asn1911, Ser1915 and Lys1918, and Ser64 and Gln73 on subunit B. In addition peptide residues Glu1913 and Lys1920 form H-bonds with Gln73 and Lys57 of subunit A. Met1910, Val1914, Leu1917 and Leu1921, which correspond to the a and d positions of the myosin-IIA coiled-coil (a – Val1914, Leu1921; d – Met1910, Leu1917), also partcipate in S100A4 binding. Met1910 and Val1914 intercalate between helices 4 and 4′ at the S100A4 dimer interface, while Leu1917 and Leu1921 insert into the hydrophobic cleft of subunit A (Figure 5B).


Structure of the S100A4/myosin-IIA complex.

Ramagopal UA, Dulyaninova NG, Varney KM, Wilder PT, Nallamsetty S, Brenowitz M, Weber DJ, Almo SC, Bresnick AR - BMC Struct. Biol. (2013)

Interactions within the S100A4Δ8C/MIIA1908-1923 complex. Binding of the MIIA1908-1923 peptide (blue) to the S100A4Δ8C dimer involves direct electrostatic interactions (A) and water mediated electrostatic interactions (not shown) as well as hydrophobic interactions (B). Hydrogen bonds are shown as red dotted lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3924328&req=5

Figure 5: Interactions within the S100A4Δ8C/MIIA1908-1923 complex. Binding of the MIIA1908-1923 peptide (blue) to the S100A4Δ8C dimer involves direct electrostatic interactions (A) and water mediated electrostatic interactions (not shown) as well as hydrophobic interactions (B). Hydrogen bonds are shown as red dotted lines.
Mentions: The 1.54 Å structure of the S100A4/MIIA1908-1923 complex revealed a single MIIA1908-1923 peptide binding across the S100A4 dimer interface (Figure 4A). Electron density was observed only for residues Asp1908-Leu1921 of the MIIA1908-1923 peptide. As shown in Figure 5A, there is an extensive H-bond network between myosin-IIA residues Asn1911, Ser1915 and Lys1918, and Ser64 and Gln73 on subunit B. In addition peptide residues Glu1913 and Lys1920 form H-bonds with Gln73 and Lys57 of subunit A. Met1910, Val1914, Leu1917 and Leu1921, which correspond to the a and d positions of the myosin-IIA coiled-coil (a – Val1914, Leu1921; d – Met1910, Leu1917), also partcipate in S100A4 binding. Met1910 and Val1914 intercalate between helices 4 and 4′ at the S100A4 dimer interface, while Leu1917 and Leu1921 insert into the hydrophobic cleft of subunit A (Figure 5B).

Bottom Line: This asymmetric binding mode was confirmed in NMR studies using a spin-labeled myosin-IIA peptide.These structural studies support the idea that residues 1908-1923 of the myosin-IIA chain heavy represent a core sequence for the S100A4/myosin-IIA complex.In addition, biophysical studies suggest that structural fluctuations within the myosin-IIA coiled-coil may facilitate S100A4 docking onto a single myosin-IIA polypeptide chain.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. anne.bresnick@einstein.yu.edu.

ABSTRACT

Background: S100A4, a member of the S100 family of Ca2+-binding proteins, modulates the motility of both non-transformed and cancer cells by regulating the localization and stability of cellular protrusions. Biochemical studies have demonstrated that S100A4 binds to the C-terminal end of the myosin-IIA heavy chain coiled-coil and disassembles myosin-IIA filaments; however, the mechanism by which S100A4 mediates myosin-IIA depolymerization is not well understood.

Results: We determined the X-ray crystal structure of the S100A4Δ8C/MIIA(1908-1923) peptide complex, which showed an asymmetric binding mode for the myosin-IIA peptide across the S100A4 dimer interface. This asymmetric binding mode was confirmed in NMR studies using a spin-labeled myosin-IIA peptide. In addition, our NMR data indicate that S100A4Δ8C binds the MIIA(1908-1923) peptide in an orientation very similar to that observed for wild-type S100A4. Studies of complex formation using a longer, dimeric myosin-IIA construct demonstrated that S100A4 binding dissociates the two myosin-IIA polypeptide chains to form a complex composed of one S100A4 dimer and a single myosin-IIA polypeptide chain. This interaction is mediated, in part, by the instability of the region of the myosin-IIA coiled-coil encompassing the S100A4 binding site.

Conclusion: The structure of the S100A4/MIIA(1908-1923) peptide complex has revealed the overall architecture of this assembly and the detailed atomic interactions that mediate S100A4 binding to the myosin-IIA heavy chain. These structural studies support the idea that residues 1908-1923 of the myosin-IIA chain heavy represent a core sequence for the S100A4/myosin-IIA complex. In addition, biophysical studies suggest that structural fluctuations within the myosin-IIA coiled-coil may facilitate S100A4 docking onto a single myosin-IIA polypeptide chain.

Show MeSH
Related in: MedlinePlus