Abstract: Described herein are methods and compositions relating to engineered curii fibers, e.g. CsgA polypeptide. In some embodiments, the methods and compositions described herein relate to functionalized biofilms. In one aspect, described herein is an engineered CsgA polypeptide, comprising a CsgA polypeptide with a C-terminal display tag flanking the CsgA polypeptide; wherein the display tag comprises an activity polypeptide and a linker sequence. In some embodiments, the display tag and/or the activity polypeptide comprises a polypeptide selected from the group consisting of metal binding domain (MBD); Spy Tag; graphene binding (GBP); carbon nanotube binding (CBP); gold binding (A3); CT43; FLAG; Z8; E14; QBP1; CLP12; and AFP8.