Escherichia coli and Salmonella spp. are a significant cause of human disease. An important virulence factor for these bacteria is curli. Curli are stable proteinacious fibers that contribute to biofilm formation, host colonization, immune activation and cell invasion. Curli also represent a compelling example of a naturally occurring amyloid fiber. Several important human diseases result from proteins that misfold into amyloid fibers. Curli assembly does not result from protein misfolding, but from a dedicated biogenesis pathway, providing a new paradigm for examining amyloidogenesis. Our long-term goal is to elucidate the molecular mechanism of curli biogenesis so that therapeutic protocols can be designed to attenuate their formation. We developed a testable model of curli assembly that suggests the major curli subunit protein CsgA is secreted from the cell as an unstructured protein that subsequently folds into a ?-sheet rich fiber on the cell surface. We hypothesize that the CsgB nucleator protein catalyzes CsgA's initial folding, but then fiber formation proceeds as a self-perpetuating process with the growing fiber tip able to serve as a template for CsgA polymerization. Secretion of CsgA and CsgB to the cell surface is dependent on the outer membrane localized CsgG protein. E. coli provides us a sophisticated genetic and biochemical system to explore the biogenesis of these unique fibers.
In Aim 1 the hypothesis that CsgB presents an amyloid-like template to CsgA during nucleation will be tested.
In Aim 2 the sequences in CsgA that facilitate its interaction with CsgB and drive its polymerization into an amyloid fiber will be determined. Finally, in Aim 3 we will test the hypothesis that CsgG forms a curli-specific secretion pore in the outer membrane. Collectively, the experiments described within this proposal will reveal the molecular and structural basis for CsgA secretion, nucleation and polymerization into a fiber. ? ? ?
|Cremers, Claudia M; Knoefler, Daniela; Gates, Stephanie et al. (2016) Polyphosphate: A Conserved Modifier of Amyloidogenic Processes. Mol Cell 63:768-80|
|Chorell, Erik; Andersson, Emma; Evans, Margery L et al. (2015) Bacterial Chaperones CsgE and CsgC Differentially Modulate Human ?-Synuclein Amyloid Formation via Transient Contacts. PLoS One 10:e0140194|
|Evans, Margery L; Chorell, Erik; Taylor, Jonathan D et al. (2015) The bacterial curli system possesses a potent and selective inhibitor of amyloid formation. Mol Cell 57:445-55|
|Spaulding, Caitlin N; Dodson, Karen W; Chapman, Matthew R et al. (2015) Fueling the Fire with Fibers: Bacterial Amyloids Promote Inflammatory Disorders. Cell Host Microbe 18:1-2|
|Goyal, Parveen; Krasteva, Petya V; Van Gerven, Nani et al. (2014) Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG. Nature 516:250-3|
|DePas, William H; Syed, Adnan K; Sifuentes, Margarita et al. (2014) Biofilm formation protects Escherichia coli against killing by Caenorhabditis elegans and Myxococcus xanthus. Appl Environ Microbiol 80:7079-87|
|Hufnagel, David A; DePas, William H; Chapman, Matthew R (2014) The disulfide bonding system suppresses CsgD-independent cellulose production in Escherichia coli. J Bacteriol 196:3690-9|
|Evans, Margery L; Chapman, Matthew R (2014) Curli biogenesis: order out of disorder. Biochim Biophys Acta 1843:1551-8|
|Hufnagel, David A; Tükel, Cagla; Chapman, Matthew R (2013) Disease to dirt: the biology of microbial amyloids. PLoS Pathog 9:e1003740|
|Zhou, Yizhou; Smith, Daniel R; Hufnagel, David A et al. (2013) Experimental manipulation of the microbial functional amyloid called curli. Methods Mol Biol 966:53-75|
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