title: Directing peptide crystallization through curvature control of nanotubes.
abstract: In the absence of efficient crystallization methods, the molecular structures of fibrous assemblies have so far remained rather elusive. In this paper, we present a rational method to crystallize the lanreotide octapeptide by modification of a residue involved in a close contact. Indeed, we show that it is possible to modify the curvature of the lanreotide nanotubes and hence their diameter. This fine tuning leads to crystallization because the radius of curvature of the initially bidimensional peptide wall can be increased up to a point where the wall is essentially flat and a crystal is allowed to grow along a third dimension. By comparing X-ray diffraction data and Fourier transform Raman spectra, we show that the nanotubes and the crystals share similar cell parameters and molecular conformations, proving that there is indeed a structural continuum between these two morphologies. These results illustrate a novel approach to crystallization and represent the first step towards the acquisition of an Å-resolution structure of the lanreotide nanotubes β-sheet assembly.
authors.affiliation: iBiTec-S, SB2SM, UMR 8221, CEA/CNRS, CEA-Saclay, 91191, Gif-sur-Yvette, France; Institut de Physique de Rennes, UMR 6251 CNRS/Université Rennes 1, Campus Beaulieu, 35042, Rennes Cedex, France; Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire (LIONS), IRAMIS, NIMBE, UMR 3299 CEA/CNRS CEA-Saclay, 91191, Gif-sur-Yvette Cedex, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gobeaux
authors.forename: Christophe
authors.initials: C
authors.lastname: Tarabout
authors.forename: Nicolas
authors.initials: N
authors.lastname: Fay
authors.forename: Cristelle
authors.initials: C
authors.lastname: Meriadec
authors.forename: Melinda
authors.initials: M
authors.lastname: Ligeti
authors.forename: David-Alexandre
authors.initials: DA
authors.lastname: Buisson
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Cintrat
authors.forename: Franck
authors.initials: F
authors.lastname: Artzner
authors.forename: Maïté
authors.initials: M
authors.lastname: Paternostre
mesh_terms: D003460:Crystallization; D008239:Lysine / Q000737:chemistry; D043942:Nanotubes / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D053838:Scattering, Small Angle; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D010456:Peptides, Cyclic; C060347:lanreotide; D013004:Somatostatin; D008239:Lysine
keywords: crystallization; diameter-control; nanotubes; self-assembly; size-control; β-sheet