Curli are major protein components of an extracellular matrix produced by many Enterobacteriaceae, including Escherichia coli and Salmonella. They play roles in adhesion, biofilm formation, and host cell invasion. Curli fibers are amyloid-like structures, unique among bacterial fibers, and are involved in host inflammatory responses. Curli biogenesis involves multiple proteins, including CsgA and CsgB, which form the fibers. Curli assembly is regulated by various environmental cues and genetic factors, including temperature, nutrient availability, and oxygen levels. Curli are essential for biofilm development and initial stages of infection. They also contribute to pathogenesis by aiding in host cell adhesion, invasion, and immune activation. Curli are involved in bacterial interactions with host proteins and can influence disease progression, such as in sepsis. Curli are also important for bacterial adhesion to plant surfaces and may contribute to foodborne infections. Curli represent a unique model system for studying bacterial amyloid formation, protein secretion, and macromolecular assembly. Their role in biofilm formation and pathogenesis highlights their importance in bacterial survival and disease.Curli are major protein components of an extracellular matrix produced by many Enterobacteriaceae, including Escherichia coli and Salmonella. They play roles in adhesion, biofilm formation, and host cell invasion. Curli fibers are amyloid-like structures, unique among bacterial fibers, and are involved in host inflammatory responses. Curli biogenesis involves multiple proteins, including CsgA and CsgB, which form the fibers. Curli assembly is regulated by various environmental cues and genetic factors, including temperature, nutrient availability, and oxygen levels. Curli are essential for biofilm development and initial stages of infection. They also contribute to pathogenesis by aiding in host cell adhesion, invasion, and immune activation. Curli are involved in bacterial interactions with host proteins and can influence disease progression, such as in sepsis. Curli are also important for bacterial adhesion to plant surfaces and may contribute to foodborne infections. Curli represent a unique model system for studying bacterial amyloid formation, protein secretion, and macromolecular assembly. Their role in biofilm formation and pathogenesis highlights their importance in bacterial survival and disease.