Structure-Function Analysis of the TibA Self-Associating Autotransporter Reveals a Modular Organization

Abstract

Some enterotoxigenic Escherichia coli strains express the TibA adhesin/invasin, a multifunctional autotransporter that mediates the autoaggregation of bacteria, biofilm formation, adhesion to cultured epithelial cells, and invasion of these cells. To elucidate the structure-function relationship in TibA, we generated mutants by transposon-based linker scanning mutagenesis and by site-directed mutagenesis. Several insertion mutants had a defect in either adhesion or autoaggregation. Mutants with a defect in autoaggregation were found in the N-terminal half of the extracellular domain, while mutants with a defect in adhesion were found in the C-terminal half. The deletion of the putative N-terminal autoaggregation domain abolished the autoaggregation of the bacteria but did not affect adhesion. The deletion of a proline-rich region located at the C terminus of the extracellular domain abolished the adhesion properties of TibA but did not affect invasion. This finding suggests that adhesion and invasion may rely on distinct mechanisms. Thus, our results reveal that TibA possesses a modular organization, with the extracellular domain being separated into an autoaggregation module and an adhesion module.

The Legionella pneumophila Collagen-Like Protein Mediates Sedimentation, Autoaggregation, and Pathogen-Phagocyte Interactions

“…Taking in account that autoaggregation is associated with increased virulence and biofilm formation in other bacterial species (14,39), we first sought to determine whether Legionella species differ in their abilities to form autoaggregates. The conventional experimental strategy to evaluate bacterial autoaggregation is to perform sedimentation assays with bacterial suspensions as aggregates settle in suspension (5,7,13). To this end, we compared the sedimentation of L. pneumophila with that of Legionella isolates from other species using a sedimentation assay adapted from a previously described method (18,19).…”

Of linkers and autochaperones: an unambiguous nomenclature to identify common and uncommon themes for autotransporter secretion

“…Due to its low sequence complexity, it is very difficult to draw conclusions regarding evolutionary conservation of this region, but high proline content could rigidify the N-termini of these linkers (Williamson, 1994). Proline-rich regions can play an important role in binding to other macromolecules, either through direct interactions or by acting as spacers (Côté and Mourez, 2011; Williamson, 1994). The proline-rich region tends to overlap with the portion of the linker found between the passenger domain and the central α-helix, although some linkers include a predicted disordered region without having a proline-rich region (Fig.…”

“… a Brandon and Goldberg (2001); Pohlner et al (1995) b Kühnel and Diezmann (2011); Ohnishi et al (1994); Oliver et al (2003b); Rutherford et al (2006); Soprova et al (2010); Teh et al (2012) c Pohlner et al (1987) d Velarde and Nataro (2004) e Côté and Mourez (2011); Ohnishi et al (1994); Thanassi et al (2005) f Besingi et al (2013); Oliver et al (2003b); Velarde and Nataro (2004) g Henderson et al (2004); Konieczny et al (2001); Maurer et al (1999); Oomen et al (2004) h Henderson et al (2004); Klauser et al (1993); Leyton et al (2012) …”

“…Inclusion of an autochaperone is predicated on it being experimentally shown to rescue folding-deficient passenger mutants when supplied in trans . Translocators correspond to the minimal units required to secrete a passenger, typically a heterologous one. a Charles et al (1989); Emsley et al (1996); Junker et al (2009, 2006); Makoff et al (1990) b Oliver et al (2003a,b); Zhai et al (2011) c Barnard et al (2007, 2012); Brockmeyer et al (2009); Dutta et al (2003); Khan et al (2011); Skillman et al (2005); Szabady et al (2005); Velarde and Nataro (2004) d Otto et al (2005); Saurí et al (2011); Soprova et al (2010); Tajima et al (2010) e Dutta et al (2003); Meza-Aguilar et al (2014); Renn et al (2012); Renn and Clark (2008) f Fink et al (2001); Meng et al (2011) g Johnson et al (2009); Klauser et al (1993, 1990); Pohlner et al (1987, 1995); van Ulsen et al (2003) h Côté and Mourez (2011); Lindenthal and Elsinghorst (1999) i Brandon and Goldberg (2001); Kühnel and Diezmann (2011); May and Morona (2008); Suzuki et al (1995); Teh and Morona (2013) j Heras et al (2014); Ramesh et al (2012); van der Woude and Henderson (2008) k Benz and Schmidt (1992); Berthiaume et al (2007); Charbonneau et al (2006); Charbonneau and Mourez (2007); Gawarzewski et al (2014); Maurer et al (1999); Rutherford et al (2006); Suhr et al (1996) l Besingi et al (2013) m van den Berg (2010); Wilhelm et al (2007, 199...…”

Recent Advances in Understanding Enteric Pathogenic Escherichia coli

“…The tib locus is also involved in adherence and invasion (736,737). More recent studies have demonstrated the involvement of TibA in autoaggregation and biofilm formation (738,739). Finally, a protein, EtpA, was found to contribute to adherence to epithelial cells and is thought to act by being transiently exposed at the tip of the flagellum to mediate attachment (740,741).…”