Table 1.
An overview of the sensing systems in E. coli that can sense properties associated with surface proximity or attachment. Only the inducing signals that may be relevant for surface sensing, as described in the section 'Surface sensing', are shown. Also, the downstream targets are limited to those that are related to biofilm formation and described in the section 'Downstream effects of the potential surface sensing pathways’.
| Sensing system | Adhesion-related inducing signals | Biofilm-related targets |
|---|---|---|
| BaeSR | Envelope stress (Raffa and Raivio 2002; Leblanc, Oates and Raivio 2011) | — |
| BarA/UvrY | Attached pili (Zhang and Normark 1996) | Motility (Suzuki et al. 2002; Weilbacher et al. 2003; Jonas et al. 2008), pili (Mitra et al. 2013) and matrix (Wang et al. 2005) |
| BasSR | pH (Perez and Groisman 2007) | Curli (Ogasawara et al. 2012) and pili (Ogasawara et al. 2012) |
| CpxAR | Osmolarity (Prigent-Combaret et al. 2001; Jubelin et al. 2005), pH (Danese and Silhavy 1998; Clarke and Voigt 2011), pili subunits (Jones et al. 1997) and envelope stress (Otto and Silhavy 2002; Hirano et al. 2007) | Motility (Raivio, Leblanc and Price 2013) and curli (Evans and Chapman 2014) |
| EnvZ/OmpR | Osmolarity (Hall and Silhavy 1981; Mizuno and Mizushima 1990; Pratt et al. 1996), pH (Heyde and Portalier 1987; Thomas and Booth 1992; Sato et al. 2000; Clarke and Voigt 2011) | Motility (Shin and Park 1995) and curli (Evans and Chapman 2014) |
| PSP | Envelope stress (Jovanovic et al. 2006) | Motility (Jovanovic et al. 2006) |
| RcsCDB | Osmolarity (Sledjeski and Gottesman 1996; Francez-Charlot et al. 2005) and envelope stress (Parker et al. 1992; Chen et al. 2001; Majdalani et al. 2005; Farris et al. 2010) | Motility (Francez-Charlot et al. 2003), curli (Evans and Chapman 2014), pili (Ferrières and Clarke 2003), Ag43 (Ferrières and Clarke 2003) and matrix (Gottesman, Trisler and Torres-Cabassa 1985) |
| Sigma factor σE | Envelope stress (Mecsas et al. 1993; Walsh et al. 2003; Lima et al. 2013) | — |
| Flagella | Hindered rotation (Lele, Hosu and Berg 2013; Tipping et al. 2013; Nord et al. 2017) | Unknown in E. coli |