Engineering protein filaments with enhanced thermostability for nanomaterials

Self-assembling protein templates have enormous potential as biomaterials for the fabrication of multifunctional nanostructures that require precise positioning of individual molecules in regular patterns over large surface areas. Furthermore, the development of protein templates that are stable under extreme conditions of heat or chemical denaturants will expand processing conditions and end-use applications for biomaterials that require exceptional stability and robustness. In the present work, we characterized the high thermal stability of a filamentous protein template, the gamma-prefoldin (gamma PFD) from the hyperthermophile Methanocaldococcus jannaschii, and subsequently used rational design to further enhance the filament's thermal stability for application as a biotemplate in the creation of platinum nanowires. The gamma PFD assembles into long fibers with lengths that exceed 2 mu m, which when heated to various temperatures and examined by transmission electron microscopy, revealed a T-m of 93 degrees C for the quaternary filament structure. Subsequently, we increased the hydrophobicity of the alpha-helices of the gamma PFD's coiled-coil, which appeared to strengthen the filamentous structure, leading to filaments of greater length at elevated temperatures. These enhanced filaments functioned as templates for the synthesis of platinum nanowires at unprecedented temperatures, and may create new opportunities for other applications of nanoscale biotemplates that require exceptional thermal stability.