ABSTRACT
Curli represent a class of highly aggregative thin surface fibres produced by many Enterobacteriaceae, serving as the proteinaceous component of the extracellular matrix. Curli are evident to confer multiple functions to bacteria, either in-host or non-host environments. Featuring a range of amyloidal characteristics, curli were classified as functional amyloids. This chapter introduces the curli extracellular matrix and their components, as well as the curli regulation and secretion. The chapter focuses on the amyloidogenic nature of curli, curli biogenesis, and the functions carried out by these fibres, in an attempt to shed light on how bacteria manage to exploit amyloid aggregation for their own benefit while avoiding the consequence associated with the uncontrolled formation of this state. Taken together, the importance of curli to aspects
of bacterial lifestyle is enormous — being a decisive factor in mediation of bacterial adhesion to a wide range of surfaces, host cells internalization, multi-cellular aggregation, pathogenesis, resistance to environmental stresses, and further to the overall biofilm architecture. It is remarkable that all these qualities are ascribed to a fold that only recently was considered one of nature’s biggest evolutionary faults.
