One approach to develop nanosystems that incorporate biological concepts involves the addition of biotic moieties (carbohydrates, DNA, protein) to abiotic scaffolds such as carbon nanotubes. These hybrids have interesting properties but incorporation of specific, site-directed functionalization is challenging and the resulting material is best described in terms of its bulk properties. An alternative approach to the development of bionanosystems is to adapt an existing biological system. This method has several advantages, including access to the powerful tools of protein engineering and ready biological acceptance as these structures themselves are biotic in origin. We have chosen the type IV pilus, a fiber-like structure from the bacteria Pseudomonas aeruginosa, as our model system for the development of a protein-based nanotube. This review highlights the biological characteristics of our model system, presents the novel features of our pilin-derived protein nanotubes, and discusses how these protein nanotubes may contribute to bionanotechnology.