YbjN protein family is structurally similar to type III secretion system chaperones
This YbjN protein family includes Escherichia coli YbjN, Erwinia amylovora AmyR, and similar proteins. YbjN proteins share a class I type III secretion chaperone (T3SC)-like fold with type III secretion system (T3SS) chaperone proteins but appear to function independently of the T3SS. YbjN is an enterobacteria-specific protein. In E. coli, it acts as a sensory transduction regulator that may play important roles in regulating bacterial multicellular behavior, metabolism, and survival under stress conditions. E. amylovora AmyR, a functionally conserved ortholog of E. coli YbjN, is a stress and virulence associated protein that regulates the ams operon. Ams proteins are required for amylovoran biosynthesis. AmyR may also regulate the Rcs phosphorelay system, an atypical two-component signal transduction (TCST) system present only in Enterobacteriaceae and positively regulates amylovoran biosynthesis by activating the ams operon transcription.
Jiyao W et al.(2023). "The conserved domain database in 2023.",