Atomic Resolution Insights into Curli Fiber Biogenesis

Taylor, J.G.; Zhou, Yizhou; Salgado, Paula S.; Patwardhan, Ardan; McGuffie, Matthew J.; Pape, Tillmann; Grabe, Grzegorz; Ashman, Elisabeth; Constable, Sean C.; Simpson, Peter; Lee, Wei Chao; Cota, Ernesto; Chapman, Matthew R.; Matthews, Stephen

doi:10.1016/j.str.2011.05.015

Cited by 80 publications

(117 citation statements)

References 59 publications

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“…The role of cysteine residues has also been investigated in E. coli curli biosynthesis (38,39). A cysteine residue is also important in the functionality of CsgG, an oligomeric protein that assembles in pore-like structures facilitating the export of major and minor curlin subunits, CsgA and CsgB.…”

Section: Discussionmentioning

confidence: 99%

“…A cysteine residue is also important in the functionality of CsgG, an oligomeric protein that assembles in pore-like structures facilitating the export of major and minor curlin subunits, CsgA and CsgB. The cysteine is proposed to be the target of CsgC, a periplasmic protein with oxidoreductase activity (39). Pairs of cysteines can oxidize to form disulfide bonds, which contribute to the correct fold and functionality of proteins (40).…”

Section: Discussionmentioning

confidence: 99%

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Functional Analysis of the Accessory Protein TapA in Bacillus subtilis Amyloid Fiber Assembly

et al. 2014

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bBacillus subtilis biofilm formation relies on the assembly of a fibrous scaffold formed by the protein TasA. TasA polymerizes into highly stable fibers with biochemical and morphological features of functional amyloids. Previously, we showed that assembly of TasA fibers requires the auxiliary protein TapA. In this study, we investigated the roles of TapA sequences from the C-terminal and N-terminal ends and TapA cysteine residues in its ability to promote the assembly of TasA amyloid-like fibers. We found that the cysteine residues are not essential for the formation of TasA fibers, as their replacement by alanine residues resulted in only minor defects in biofilm formation. Mutating sequences in the C-terminal half had no effect on biofilm formation. However, we identified a sequence of 8 amino acids in the N terminus that is key for TasA fiber formation. Strains expressing TapA lacking these 8 residues were completely defective in biofilm formation. In addition, this TapA mutant protein exhibited a dominant negative effect on TasA fiber formation. Even in the presence of wild-type TapA, the mutant protein inhibited fiber assembly in vitro and delayed biofilm formation in vivo. We propose that this 8-residue sequence is crucial for the formation of amyloid-like fibers on the cell surface, perhaps by mediating the interaction between TapA or TapA and TasA molecules.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Functional Analysis of the Accessory Protein TapA in Bacillus subtilis Amyloid Fiber Assembly

et al. 2014

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“…Here, we report the crystal structure of E. coli CsgG, the main transmembrane (TM) component of the type VIII secretion system. This 30-kDa lipoprotein is targeted to the OM, where it was thought to form a translocation channel of 2-nm diameter via oligomerization (14,17). Our structural analysis reveals a large TM β-barrel structure, with a putative selection filter located at the OM-periplasm interface inside the barrel, representing, to our knowledge, the first core structure of the type VIII bacterial secretion machinery.…”

mentioning

confidence: 84%

“…In addition, CsgD is a transcriptional factor regulating the csgBAC operon (10), presumably coordinating the timely expression of both csg operons. CsgC, the crystal structure of which has recently been reported (17), is a putative oxidoreductase, although its exact function during curli biogenesis remains illdefined. In summary, the curli biogenesis pathway represents a unique class among the bacterial protein secretion machineries, both from a structural as well as a mechanistic perspective.…”

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confidence: 99%

Structure of the nonameric bacterial amyloid secretion channel

Cao

Zhao

Kou

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

102

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Various strains of bacteria are able to produce a unique class of functional amyloids termed curli, which are critical for biofilm formation, host cell adhesion, and colonization of inert surfaces. Curli are secreted via the type VIII bacterial secretion system, and they share biochemical and structural characteristics with amyloid fibers that have been implicated in deleterious disease in humans. Here, we report the crystal structure of Escherichia coli CsgG, which is an essential lipoprotein component of the type VIII secretion system and which forms a secretion channel in the bacterial outer membrane for transporting curli subunits. CsgG forms a crown-shaped, symmetric nonameric channel that spans the outer membrane via a 36-strand β-barrel, with each subunit contributing four β-strands. This nonameric complex contains a central channel with a pore located at the middle. The eyelet of the pore is ∼12 Å in diameter and is lined with three stacked nine-residue rings consisting of Tyr-66, Asn-70, or Phe-71. Our structure-based functional studies suggest that Tyr-66 and Phe-71 residues function as gatekeepers for the selective secretion of curli subunits. Our study describes in detail, to our knowledge, the first core structure of the type VIII bacterial secretion machinery. Importantly, our structural analysis suggests that the curli subunits are secreted via CsgG across the bacterial outer membrane in an unfolded form.CsgG | curli | amyloids | outer membrane protein | biofilm

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“…The CsgC structure is homologous to the N-terminal region of the redox protein DsbD that forms a ␤-sandwich with a hydrophobic core (63). It is possible that CsgC utilizes the same mechanism as most chaperones by displaying hydrophobic segments to interact with the unfolded substrate.…”

Section: Insights Into the Molecular Mechanism Of The Csgc Chaperonementioning

confidence: 99%

Specific Chaperones and Regulatory Domains in Control of Amyloid Formation

Landreh

Rising

Presto

et al. 2015

Journal of Biological Chemistry

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Many proteins can form amyloid-like fibrils in vitro, but only about 30 amyloids are linked to disease, whereas some proteins form physiological amyloid-like assemblies. This raises questions of how the formation of toxic protein species during amyloidogenesis is prevented or contained in vivo. Intrinsic chaperoning or regulatory factors can control the aggregation in different protein systems, thereby preventing unwanted aggregation and enabling the biological use of amyloidogenic proteins. The molecular actions of these chaperones and regulators provide clues to the prevention of amyloid disease, as well as to the harnessing of amyloidogenic proteins in medicine and biotechnology.

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Atomic Resolution Insights into Curli Fiber Biogenesis

Cited by 80 publications

References 59 publications

Functional Analysis of the Accessory Protein TapA in Bacillus subtilis Amyloid Fiber Assembly

Functional Analysis of the Accessory Protein TapA in Bacillus subtilis Amyloid Fiber Assembly

Structure of the nonameric bacterial amyloid secretion channel

Specific Chaperones and Regulatory Domains in Control of Amyloid Formation

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