Biological proteins and peptides have the intrinsic ability to self-assemble into elongated solid nanofibrils(1-7), which may give rise to amyloid diseases(8-11) or inspire applications ranging from tissue engineering to nanoelectronics(12-16). Proteinaceous fibrils are extensively studied and well understood, to the extent that detailed theoretical models have been proposed that explain and predict their behavior(17,18). Another intriguing state of protein-like self-assembly is that of nanotubes (NTs), defined here as an elongated nano-object with a definite inner hole. In contrast to proteinaceous fibrils, nanotubes are much less frequently observed and far less well understood. However, they have attracted research interest internationally as key components for nanotechnology.