Escherichia coli Type III Secretion System 2 ATPase EivC Is Involved in the Motility and Virulence of Avian Pathogenic Escherichia coli

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.

Escherichia coli ST302: Genomic Analysis of Virulence Potential and Antimicrobial Resistance Mediated by Mobile Genetic Elements

“…F2_18C possesses the full complement of ETT2 genes (Figure 5A), however an IS1F insertion interrupts the eivG gene, and eivC gene is truncated. The latter observation may be particularly important as eivC is involved in motility, serum resistance and intramacrophage survival, at least in avian pathogenic E. coli (APEC) (Wang et al, 2016).…”

Comparative Genomic Analysis of Globally Dominant ST131 Clone with Other Epidemiologically Successful Extraintestinal Pathogenic Escherichia coli (ExPEC) Lineages

“…2 ). Also, Wang et al demonstrated that the components of the type 3 secretion system (T3SS) play roles in virulence and intracellular survival of an avian-pathogenic E. coli (APEC) strain in macrophages ( 49 ); thus, roles of such factors might also influence adhesion and invasion of ExPEC strains. In Gram-negative bacteria, the majority of serine proteases secreted by the autotransporter pathway are implicated in virulence ( 50 ).…”

A highly conserved complete accessory Escherichia coli type III secretion system 2 is widespread in bloodstream isolates of the ST69 lineage

“…Mutational analysis of the ETT2 cluster in an avian pathogenic E. coli showed it had reduced virulence, even though the cluster had undergone mutational attrition and could not encode a functional T3SS, suggesting potential alternative roles in pathogenesis 19 . Other studies have also suggested a role for proteins encoded in the ETT2 in virulence of avian pathogenic E. coli and K1 strains [20][21][22] . A recent study examined the role of the putative transcriptional regulator gene eilA at the selC locus in EAEC strain O42 18 .…”