Type IV Pili Promote Clostridium difficile Adherence and Persistence in a Mouse Model of Infection

Abstract

Cyclic diguanylate (c-di-GMP) is a second messenger that regulates the transition from motile to sessile lifestyles in numerous bacteria and controls virulence factor production in a variety of pathogens. In , c-di-GMP negatively regulates flagellum biosynthesis and swimming motility and promotes the production of type IV pili (TFP), biofilm formation, and surface motility Flagella have been identified as colonization factors in , but the role of TFP in adherence to host cells and in colonization of the mammalian gut is unknown. Here we show that c-di-GMP promotes adherence to epithelial cells, which can be partly attributed to the loss of flagella. Using TFP-null mutants, we demonstrate that adherence to epithelial cells is partially mediated by TFP and that this TFP-mediated adherence requires c-di-GMP regulation. In a mouse model of colonization, the TFP-null mutants initially colonized the intestine as well as the parental strain but were cleared more quickly. Moreover, compared to the parent strain, strains lacking TFP were particularly deficient in association with the cecal mucosa. Together these data indicate that TFP and their positive regulation by c-di-GMP promote attachment of to the intestinal epithelium and contribute to persistence of in the host intestine.

Phase variation of a signal transduction system controlsClostridioides difficilecolony morphology, motility, and virulence

“…C. difficile spores were collected from 70:30 sporulation broth after 3 days of growth (79). The spores were purified using a sucrose gradient and stored in PBS with 1% bovine serum albumin as described previously (44, 80). Prior to inoculation, the spores were enumerated by plating serial dilutions on BHIS-agar containing 0.1% sodium taurocholate.…”

“…Because flagellum and toxin gene expression is linked through SigD, c-di-GMP also inhibits toxin production (34, 43). Conversely, a c-di-GMP riboswitch upstream of the Type IV pilus (TFP) locus allows c-di-GMP to positively regulate gene expression and promote TFP-dependent behaviors such as autoaggregation, surface motility, biofilm formation, and colonization of host tissues (33, 35–37, 43, 44). Additionally, c-di-GMP regulates the expression and cell wall anchoring of surface proteins and adhesins (41, 45, 46).…”

Monoderm bacteria: the new frontier for type IV pilus biology

“…These findings directly implicate C. perfringens Tfpa, more specifically PilA2, in the ability of this species to adhere to muscle fibres, which is key to its pathogenic potential. Similarly, Tfpa were found to promote (i) the adherence of C. difficile to human intestinal epithelial cells and persistence in the intestine (McKee et al, 2018), and (ii) the binding of S. sanguinis to human cells (Chen et al, 2019). It is not known which pilus component mediates binding, but the presence of very large (>50 kDa) minor pilins with a 'modular' architecture, that is, with bulky C-terminal functional domains, is certainly an intriguing possibility.…”

Caldicellulosiruptor besciiregulates pilus expression in response to the polysaccharide, xylan

“…Recently, the ATPases required for twitching motility in C. perfringens were found to be upregulated in response to colonization and necrosis of murine muscle tissue 90 (33), supporting the role of C. perfringens T4P adherence to muscle cells. Furthermore, C. difficile ΔpilA1 mutants, lacking T4P, were significantly reduced in their ability to attach to epithelial cells (32).…”

“…Genes required for assembly of a Gram-negative like T4P are fairly widespread throughout the genus Clostridium (28,29), including the pathogens Clostridium perfringens (28) and C. difficile (30). Major pilins from both C. perfringens (31) and C. difficile (32) have been demonstrated to play a role in adhesion, and heterologous expression of the C. perfringens 85 major pilin gene, pilA2, in T4P-deficient Neisseria gonorrhoea mutants resulted in attachment to muscle cells (31). Since complemented N. gonorrhea were capable of new cell-adherence specificity, but not twitching motility, there appears to be a limitation to the conserved structure and function of pilins.…”