Abstract
Type III secretion systems (T3SSs) are crucial for bacterial infections because they deliver effector proteins into host cells. The Escherichia coli type III secretion system 2 (ETT2) is present in the majority of E. coli strains, and although it is degenerate, ETT2 regulates bacterial virulence. An ATPase is essential for T3SS secretion, but the function of the ETT2 ATPase has not been demonstrated. Here, we show that EivC is homologous to the β subunit of F0F1 ATPases and it possesses ATPase activity. To investigate the effects of ETT2 ATPase EivC on the phenotype and virulence of avian pathogenic Escherichia coli (APEC), eivC mutant and complemented strains were constructed and characterized. Inactivation of eivC led to impaired flagella production and augmented fimbriae on the bacterial surface, and, consequently, reduced bacterial motility. In addition, the eivC mutant strain exhibited attenuated virulence in ducks, diminished serum resistance, reduced survival in macrophage cells and in ducks, upregulated fimbrial gene expression, and downregulated flagellar and virulence gene expression. The expression of the inflammatory cytokines interleukin (IL)-1β and IL-8 were increased in HD-11 macrophages infected with the eivC mutant strain, compared with the wild-type strain. These virulence-related phenotypes were restored by genetic complementation. These findings demonstrate that ETT2 ATPase EivC is involved in the motility and pathogenicity of APEC.
Highlights
A number of Gram-negative pathogens, such as Escherichia coli (E. coli), Salmonella, Yersinia, and Pseudomonas utilize type III secretion systems (T3SSs) to deliver effector proteins into eukaryotic host cells and to assemble flagella, which facilitate infections and bacterial motility (Mota and Cornelis, 2005; Diepold and Armitage, 2015)
Like other T3SS ATPases, EivC is homologous to the β subunit of F0F1 ATPases and it possesses ATPase activity
Our previous study verified that the prevalence of Escherichia coli type III secretion system 2 (ETT2) in avian pathogenic Escherichia coli (APEC), similar to intestinal pathogenic E. coli, was markedly higher than that in human extraintestinal pathogenic E. coli (ExPEC) (UPEC and newborn meningitis E. coli (NMEC)); it might be a potential risk to human health (Wang et al, 2016)
Summary
A number of Gram-negative pathogens, such as Escherichia coli (E. coli), Salmonella, Yersinia, and Pseudomonas utilize type III secretion systems (T3SSs) to deliver effector proteins into eukaryotic host cells and to assemble flagella, which facilitate infections and bacterial motility (Mota and Cornelis, 2005; Diepold and Armitage, 2015). T3SSs have an extracellular, needle-like projection connecting to the basal body, which serves as a channel for the translocation of effector proteins. These bacterial effector proteins interact and subvert the innate immunity of host cells, thereby facilitating bacterial growth and survival, which subsequently lead to diseases. It has been shown that ATPases are involved in the unfolding of effector proteins before their secretion (Minamino and MacNab, 2000; Jouihri et al, 2003; Akeda and Galan, 2005; Pallen et al, 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
