The structure of a polyQ–anti-polyQ complex reveals binding according to a linear lattice model

Li, Pingwei; Huey-Tubman, Kathryn E.; Gao, Tiyu; Li, Xiaojun; West, Anthony P.; Bennett, M. J.; Björkman, Pamela J.

doi:10.1038/nsmb1234

Cited by 65 publications

(87 citation statements)

References 49 publications

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“…Alternatively, a technical explanation for this result might be poor staining by 1C2. It has been suggested that anti-polyQ antibodies do not detect the polyQ peptide itself, but interact with the secondary structure created by the expanded polyQ peptide (Li et al, 2007). Nonetheless, we showed that the 1C2 antibody was able to recognize a Q16 peptide fused to GFP with almost equal efficiency as GFP-Q65 and GFP-Q112 proteins.…”

Section: Journal Of Cell Science 122 (18)mentioning

confidence: 63%

Mimicking proteasomal release of polyglutamine peptides initiates aggregation and toxicity

Raspe

Gillis

Krol

et al. 2009

Journal of Cell Science

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Several neurodegenerative disorders, including Huntington's disease, are caused by expansion of the polyglutamine (polyQ) tract over 40 glutamines in the disease-related protein.Fragments of these proteins containing the expanded polyQ tract are thought to initiate aggregation and represent the toxic species. Although it is not clear how these toxic fragments are generated, in vitro data suggest that proteasomes are unable to digest polyQ tracts. To examine whether the resulting polyQ peptides could initiate aggregation in living cells, we mimicked proteasomal release of monomeric polyQ peptides. These peptides lack the commonly used starting methionine residue or any additional tag. Only expanded polyQ peptides seem to be peptidase resistant, and their accumulation initiated the aggregation process. As observed in polyQ disorders, these aggregates subsequently sequestered proteasomes, ubiquitin and polyQ proteins, and recruited Hsp70. The generated expanded polyQ peptides were toxic to neuronal cells. Our approach mimics proteasomal release of pure polyQ peptides in living cells, and represents a valuable tool to screen for proteins and compounds that affect aggregation and toxicity.Supplementary material available online at

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Section: Journal Of Cell Science 122 (18)mentioning

confidence: 63%

Mimicking proteasomal release of polyglutamine peptides initiates aggregation and toxicity

Raspe

Gillis

Krol

et al. 2009

Journal of Cell Science

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“…The calculated shape correlation statistics (Sc, a measure of the degree that two contacting surfaces are geometrically matched) is 0.70, where an Sc value of 1.0 indicates a perfect fit (28). The buried surface area and shape complementarity between LGP2 and dsRNA are comparable with typical antibody⅐peptide antigen complexes, which have an average buried surface area of 1430 Å 2 and an Sc of 0.75 (29). Structure of LGP2 C-terminal Domain-Although the amino acid sequences of LGP2 and RIG-I CTD are only 25% identical (supplemental Fig.…”

Section: Overall Structure Of Thementioning

confidence: 79%

The RIG-I-like Receptor LGP2 Recognizes the Termini of Double-stranded RNA

Ranjith-Kumar

Brooks

et al. 2009

Journal of Biological Chemistry

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142

163

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The RIG-I-like receptors (RLRs), RIG-I and MDA5, recognize single-stranded RNA with 5 triphosphates and doublestranded RNA (dsRNA) to initiate innate antiviral immune responses.LGP2, a homolog of RIG-I and MDA5 that lacks signaling capability, regulates the signaling of the RLRs. To establish the structural basis of dsRNA recognition by the RLRs, we have determined the 2.0-Å resolution crystal structure of human LGP2 C-terminal domain bound to an 8-bp dsRNA. Two LGP2 C-terminal domain molecules bind to the termini of dsRNA with minimal contacts between the protein molecules. Gel filtration chromatography and analytical ultracentrifugation demonstrated that LGP2 binds blunt-ended dsRNA of different lengths, forming complexes with 2:1 stoichiometry. dsRNA with protruding termini bind LGP2 and RIG-I weakly and do not stimulate the activation of RIG-I efficiently in cells. Surprisingly, full-length LGP2 containing mutations that abolish dsRNA binding retained the ability to inhibit RIG-I signaling.The innate immune response is the first line of defense against invading pathogens; it is the ubiquitous system of defense against microbial infections (1). Toll-like receptors (TLRs) 3 and RIG-I (retinoic acid-inducible gene 1)-like receptors (RLRs) play key roles in innate immune response toward viral infection (2-5). Toll-like receptors TLR3, TLR7, and TLR8 sense viral RNA released in the endosome following phagocytosis of the pathogens (6). RIG-I-like receptors RIG-I and MDA5 detect viral RNA from replicating viruses in infected cells (3,7,8). Stimulation of these receptors leads to the induction of type I interferons (IFNs) and other proinflammatory cytokines, conferring antiviral activity to the host cells and activating the acquired immune responses (4, 9).RIG-I discriminates between viral and host RNA through specific recognition of the uncapped 5Ј-triphosphate of singlestranded RNA (5Ј ppp ssRNA) generated by viral RNA polymerases (10, 11). In addition, RIG-I also recognizes doublestranded RNA generated during RNA virus replication (7,12). Transfection of cells with synthetic double-stranded RNA stimulates the activation of RIG-I (13, 14). Synthetic dsRNA mimics, such as polyinosinic-polycytidylic acid (poly(I⅐C)), can activate MDA5 when introduced into the cytoplasm of cells. Digestion of poly(I⅐C) with RNase III transforms poly(I⅐C) from a ligand for MDA5 into a ligand for RIG-I, suggesting that MDA5 recognizes long dsRNA, whereas RIG-I recognizes short dsRNA (15). Studies of RIG-I and MDA5 knock-out mice confirmed the essential roles of these receptors in antiviral immune responses and demonstrated that they sense different sets of RNA viruses (12, 16).RIG-I and MDA5 contain two caspase recruiting domains (CARDs) at their N termini, a DEX(D/H) box RNA helicase domain, and a C-terminal regulatory or repressor domain (CTD). The helicase domain and the CTD are responsible for viral RNA binding, whereas the CARDs are required for signaling (3, 8). The current model of RIG-I activation suggests that under resting ...

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“…S1C); its binding resembled the binding of MW1 (Fig. S1D), one of a group of anti-poly Q mouse IgM that express Vλx and bind to the Golgi complex (17,27). The similarity between the +2 scFv and MW1 IgM binding suggested that the Vλx contributes to Golgi binding, even in the context of a different V H .…”

Section: Resultsmentioning

confidence: 94%

“…Because all three Abs use the CJ Vλx, we avoided uncertainties associated with structural modeling. The Vλx participates in binding to a peptide from the Ebola virus (28), the parathyroid hormonerelated peptide (PHRP) (29), and a poly-Q sequence (17). Intriguingly, each of these diverse Ags follows a similar path across the combining site, which runs perpendicular to the Vλx L3 (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Antibodies that bind complex glycosaminoglycans accumulate in the Golgi

Radic

Weigert

Khan

et al. 2013

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

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Light (L) chains that edit anti-DNA heavy (H) chains rescue B-cell development by suppressing DNA binding. However, exceptional editor L chains allow B cells to reach splenic compartments even though their B-cell receptors remain autoreactive. Such incompletely edited B cells express multireactive antibodies that accumulate in the Golgi and are released as insoluble, amyloid-like immune complexes. Here, we examine examples of incomplete editing from the analysis of variable to joining (VJ) gene junction of the variable (Vλx) editor L chain. When paired with the anti-DNA heavy chain, V H 56R, the Vλx variants yield antibodies with differing specificities, including glycosaminoglycan reactivity. Our results implicate these specificities in the evasion of receptor editing through intracellular sequestration of IgM and the release of insoluble IgM complexes. Our findings can be extrapolated to human L chains and have implications for understanding a latent component of the Ig repertoire that could exert pathogenic and protective functions.

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The structure of a polyQ–anti-polyQ complex reveals binding according to a linear lattice model

Cited by 65 publications

References 49 publications

Mimicking proteasomal release of polyglutamine peptides initiates aggregation and toxicity

Mimicking proteasomal release of polyglutamine peptides initiates aggregation and toxicity

The RIG-I-like Receptor LGP2 Recognizes the Termini of Double-stranded RNA

Antibodies that bind complex glycosaminoglycans accumulate in the Golgi

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