| Outline of Final Research Achievements |
Enteric bacteria synthesize extracellular functional amyloids, curli, during biofilm formation and host colonization. Although aggregation of the major curli subunit, CsgA, is prevented by cytoplasmic and periplasmic molecular chaperones, its degradation in cells remains unclear. Here, using genomically engineered E. coli and multicopy-suppressor screening, we discovered that serine proteases Prc is involved in degradation of CsgA in the periplasm. Expression of the csg operon is down-regulated at the transcription level under the situations where CsgA aggregates could accumulate in the periplasm. In addition, production of extracellular membrane vesicles was stimulated under the similar situations. Furthermore, we proposed functional hierarchy of J-domain proteins that work with molecular chaperone DnaK in regulation of curli biosynthesis.
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