Proline-Rich Salivary Proteins Have Extended Conformations

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Boze, Helene | Marlin, Therese | Durand Dominique, Dominique | Perez, Javier | Vernhet, Aude | Canon, Francis | Manchado-Sarni, Pascale | Cheynier, Veronique, V. | Cabane, Bernard

Edité par CCSD ; Biophysical Society -

Biophys. J. ISI Document Delivery No.: 629GD Times Cited: 16 Cited Reference Count: 60 Boze, Helene Marlin, Therese Durand, Dominique Perez, Javier Vernhet, Aude Canon, Francis Sarni-Manchado, Pascale Cheynier, Veronique Cabane, Bernard French Agence Nationale de la Recherche [07-BLAN-02]; European Commission [RIDS 011934] This work was supported by the French Agence Nationale de la Recherche (07-BLAN-02 to A.N.R.), and the European Commission Sixth Framework Programme (RIDS 011934 to J.P.). Cell press Cambridge. International audience. Three basic proline-rich salivary proteins have been produced through the recombinant route. IB5 is a small basic proline-rich protein that is involved in the binding of plant tannins in the oral cavity. II-1 is a larger protein with a closely related backbone; it is glycosylated, and it is also able to bind plant tannins. II-1ng has the same polypeptidic backbone as II-1, but it is not glycosylated. Small angle x-ray scattering experiments on dilute solutions of these proteins confirm that they are intrinsically disordered. IB5 and II-1ng can be described through a chain model including a persistence length and cross section. The measured radii of gyration (R(g) = 27.9 and 41.0 +/- 1 angstrom respectively) and largest distances (r(max) = 110 and 155 +/- 10 angstrom respectively) show that their average conformations are rather extended. The length of the statistical segment (twice the persistence length) is b = 30 angstrom, which is larger than the usual value (18 angstrom - 20 angstrom) for unstructured polypeptide chains. These characteristics are presumably related to the presence of polyproline helices within the polypeptidic backbones. For both proteins, the radius of gyration of the chain cross-section is R(c) = 2.7 +/- 0.2 angstrom. The glycosylated protein II-1 has similar conformations but the presence of large polyoside sidegroups yields the structure of a branched macromolecule with the same hydrophobic backbone and hydrophilic branches. It is proposed that the unusually extended conformations of these proteins in solution facilitate the capture of plant tannins in the oral cavity.

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