The c-di-GMP Metabolic Gene pdeN Interacts with LacY and ManZ to Modulate Biofilm Formation in Avian Pathogenic Escherichia coli.

Bis-(3'-5')-cyclic diguanylic acid (c-di-GMP), a ubiquitous secondary messenger, affects multiple biological characteristics, including biofilm formation in avian pathogenic Escherichia coli (APEC). C-di-GMP is synthesized by diguanylate cyclase harboring a GGDEF domain and degraded by phosphodiesterase harboring either an EAL or an HD-GYP domain. However, the roles of PdeN, encoding a CSS-EAL domain, are uncharacterized. In this study, it is demonstrated that lacking pdeN significantly promotes biofilm formation and reduces the motility of the clinically isolated APEC O2 serotype strain DE17. In addition, macrocolony morphotypes showed that the ΔpdeN strain exhibits increasing production of curli fibers and cellulose, which is consistent with the results of RNA-seq and qPCR. Further exploration shows that lactose permease LacY and mannose permease subunit ManZ interact with PdeN. Infection experiments show that lacking pdeN significantly reduced the release of LDH in HD-11 cells and adhesion capacity to DF-1 cells. In conclusion, c-di-GMP metabolic gene pdeN involves biofilm formation and pathogenicity of APEC. Besides, it interacts with LacY and ManZ. Those results provide a basis for the prevention and control of APEC from the perspective of biofilm and carbohydrate metabolism.