Experimental observation of double-walled peptide nanotubes and monodispersity modeling of the number of walls.
Self-assembled nanoarchitectures based on biological molecules are attractive because of the simplicity and versatility of the building blocks. However, size control is still a challenge. This control is only possible when a given system is deeply understood. Such is the case with the lanreotide acetate, an octapeptide salt that spontaneously forms monodisperse nanotubes when dissolved into pure water. Following a structural approach, we have in the past demonstrated the possibility to tune the diameter of these nanotubes while keeping a strict monodispersity, either by chemical modification of one precise amino acid on the peptide sequence or by changing the size of the counterions. On the basis of these previous studies, we replaced monovalent counterions by divalent ones to vary the number of walls. Indeed, in the present work, we show that lanreotide associated with a divalent counterion forms double-walled nanotubes while keeping the average diameter constant. However, the strict monodispersity of the number of walls was unexpected. We propose that the divalent counterions create an adhesion force that can drive the wall packing. This adhesion force is counterbalanced by a mechanical one that is related to the stiffness of the peptide wall. By taking into account these two opposite forces, we have built a general model that fully explains why the lanreotide nanotubes formed with divalent counterions possess two walls and not more.
Institut de Biologie et de Technologies de Saclay/Service de Bioénergétique, Biologie Structurale et Mécanismes, UMR 8221 CNRS and CEA, CEA-Saclay, 91191 Gif-sur-Yvette, France.
Frédéric
F
Gobeaux
Nicolas
N
Fay
Christophe
C
Tarabout
Florian
F
Meneau
Cristelle
C
Mériadec
Camille
C
Delvaux
Jean-Christophe
JC
Cintrat
Céline
C
Valéry
Franck
F
Artzner
Maïté
M
Paternostre
D008958:Models, Molecular; D008968:Molecular Conformation; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D010455:Peptides / Q000737:chemistry*; D013499:Surface Properties
D010455:Peptides