Regulation of poly-GlcNAc expression and fimbriation in uropathogenic "E. coli"

The transition of planktonic to sessile lifestyles in bacteria rests upon a tightly controlled program that gets triggered by the environmental composition and whose implementation requires multiple feedback controls. Uropathogenic E. coli (UPEC), the predominant agents of urinary tract infections, use this lifestyle switch to shift from acute to chronic, biofilm associated infections. While the acute phase of infection is dominated by the expression of virulence factors such as type I fimbriae, biofilm matrix components including PGA prevail during biofilm associated infections. In this work, factors reported to induce a lifestyle switch are used in UPECs to investigate their effects on the expression patterns of two output-systems (type I fimbriae and PGA) during lifestyles transition. It was investigated if PGA dependent biofilm formation in UPECs requires derepression of the carbon storage regulator (Csr) system. Furthermore, it was analysed if PGA dependent biofilms respond to the bacterial second messenger c-di-GMP or the alarmone ppGpp of the stringent response and if PGA contributes to UTI pathogenesis. Finally, this work aims at clarifying the role of type I fimbriae in PGA dependent attachment and investigates if the expression patterns of the two surface-exposed structures are subject to a regulatory cross-talk.