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See detailNanobodies as structural probes to investigate the mechanism of fibril formation by the amyloidogenic variants of human lysozyme
Dumont, Janice ULg; pardon, Els; Aumont-Nicaise, Magali et al

Poster (2012, June)

Six variants of human lysozyme (single-point mutatants I56T, F57I, W64R, D67H and double mutants F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These ... [more ▼]

Six variants of human lysozyme (single-point mutatants I56T, F57I, W64R, D67H and double mutants F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. We have also shown that the binding of three variable domain of camelid antibodies (VHHs) - raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three VHHs bind on different regions of lysozyme and act as amyloid fibril inhibitor through different mechanisms [2, 3, and unpublished results]. In the present work, sixteen new VHHs specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non-overlapping epitopes. We have demonstrated that five of these VHHs are able to bind lysozyme in conditions used for amyloid fibril formation, and interestingly two of them recognize two epitopes that are different from those of the three VHHs previously characterized [2, 3, and unpublished results]. The effects of these new VHHs on the properties of lysozyme variants such as stability, cooperativity and aggregation will be discussed. [1] Dumoulin, M., J.R. Kumita, and C.M. Dobson, Normal and aberrant biological self-assembly: Insights from studies of human lysozyme and its amyloidogenic variants. Acc Chem Res, 2006, 39(9), 603-610. [2] Dumoulin, M., et al., A camelid antibody fragment inhibits the formation of amyloid fibrils by human lysozyme. Nature, 2003, 424, 783-788. [3] Chan, P.H., et al., Engineering a camelid antibody fragment that binds to the active site of human lysozyme and inhibits its conversion into amyloid fibrils. Biochemistry, 2008, 47, 11041-11054. [less ▲]

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See detailVHHs as structural probes to investigate the mechanis of fibril formation by the amyloidogenic variants of human lysozyme
Dumont, Janice; Kumita, Janet; Menzer, Linda et al

Scientific conference (2011, August 26)

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See detailNanobodies as structural probes to investigate the mechanism of fibril formation by the amyloidogenic variants of human lysozyme
Dumont, Janice ULg; Pardon, Els; Aumont-Nicaise, Magalie et al

Poster (2011)

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These ... [more ▼]

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. We have also shown that the binding of three variable domain of camelid antibodies or (VHHs) - raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three VHHs bind on different regions of lysozyme and act as amyloid fibrils inhibitor through different mechanisms [2, 3, and unpublished results]. In the present work, sixteen new VHHs specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non overlapping epitopes. We have demonstrated that five of these new VHHs are able to bind lysozyme in conditions used for amyloid fibril formation, and interestingly two of them recognize two epitopes that are different from those of the three VHHs previously characterized [2, 3, and unpublished results]. The effects of these new VHHs on the properties of lysozyme variants such as activity, stability, cooperativity and aggregation will be discussed. [less ▲]

Detailed reference viewed: 45 (1 ULg)
See detailCamelid single-domain antibody fragments as structural probes to study the mechanism of human lysozyme fibrils formation
Dumont, Janice ULg; Pardon, Els; Menzer, Linda ULg et al

Poster (2010)

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These ... [more ▼]

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidosis. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. The binding of three variable domain of camelid antibodies – also named nanobodies - (cAb-HuL 6 [2], cAb-HuL 5 and cAb-HuL 22 [3]) raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three nanobodies bind on different regions of lysozyme and act as amyloid fibrils inhibitor through different mechanisms. On one hand, cAb-HuL 6 and cAb-HuL 22 stabilize the native state of the lysozyme variants thus restoring the global cooperativity characteristic of the wild-type protein. On the other, cAb-HuL 5 probably acts by binding soluble prefibrillar aggregates. In the present work, sixteen other nanobodies specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non overlapping epitopes. The effects of the binding of these nanobodies on the stability of the D67H variant of human lysozyme and on its aggregation into amyloid fibrils will be discussed. References [1] Dumoulin et al, (2006) Acc. Chem. Res, 39, 603-610. [2] Dumoulin et al, (2003) Nature, 424, 783-788. [3] Chan et al. (2008) Biochemistry, 47,11041-11054. [less ▲]

Detailed reference viewed: 28 (2 ULg)
See detailNanobodies as structural probes to investigate the mechanism of fibril formation by the amyloidogenic variants of human lysozyme.
Dumont, Janice ULg; Menzer, Linda ULg; Pardon, Els et al

Poster (2010)

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These ... [more ▼]

Six variants of human lysozyme (single-point mutations I56T, F57I, W64R, D67H and double mutations F57I/T70N, W112R/T70N) are associated with a hereditary non-neuropathic systemic amyloidose. These proteins form extracellular amyloid fibrils that deposit in a wide range of tissues and organs such as liver, spleen and kidneys where they cause damages [1]. It was shown that the D67H and I56T mutations cause a loss in stability and more particularly a loss of global cooperativity of protein [1]. Consequently, under physiologically relevant conditions, these variants can transiently populate a partially unfolded state in which the beta-domain and the C-helix are cooperatively unfolded while the rest of the protein remains native like [1]. The formation of intermolecular interactions between the regions that are unfolded in this intermediate state is likely to be a fundamental trigger of the aggregation process that ultimately leads to the formation and deposition of fibrils in tissues. The binding of three variable domain of camelid antibodies – also named nanobodies - (cAb-HuL 6 [2], cAb-HuL 5 and cAb-HuL 22 [3]) raised against the wild type human lysozyme inhibit in vitro the formation of amyloid fibrils by the lysozyme variants. These three nanobodies bind on different regions of lysozyme and act as Amyloid fibrils inhibitor through different mechanisms. On one hand, cAb-HuL 6 and cAb-HuL 22 stabilize the native state of the lysozyme variants thus restoring the global cooperativity characteristic of the wild-type protein. On the other, cAb-HuL 5 probably acts by binding soluble prefibrillar aggregates. In the present work, sixteen other nanobodies specific of human lysozyme have been generated. Competition experiments have shown that they bind to five non overlapping epitopes. The effects of the binding of these nanobodies on the stability of the D67H variant of human lysozyme and on its aggregation into amyloid fibrils will be discussed. [less ▲]

Detailed reference viewed: 40 (1 ULg)
See detailHuman lysozyme amyloidosis
Dumoulin, Mireille ULg; Johnson, Russell J.K.; Bellotti, Vittorio et al

in Uversky, V.; Fink, A. L. (Eds.) Protein Misfolding, Aggregation and Conformational Diseases. II. Molecular Basis of Conformational Diseases. (2007)

Detailed reference viewed: 20 (3 ULg)
See detailHereditary systemic amyloidosis associated with mutational variants of human lysozyme
Dumoulin, Mireille ULg; Bellotti, Vittorio; Dobson, Christopher

in Sipe, J. (Ed.) In Amyloid Proteins: The Beta Pleated Sheet Conformation and Disease (2005)

Detailed reference viewed: 11 (0 ULg)
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See detailProbing the origins, diagnosis and treatment of amyloid diseases using antibodies.
Dumoulin, Mireille ULg; Dobson, Christopher

in Biochimie (2004), 86

The deposition of proteins in the form of amyloid fibrils is the characteristic feature of more than 20 medical conditions affecting the central nervous system or a variety of peripheral tissues. These ... [more ▼]

The deposition of proteins in the form of amyloid fibrils is the characteristic feature of more than 20 medical conditions affecting the central nervous system or a variety of peripheral tissues. These disorders, which include Alzheimer's disease, the prion diseases and type II diabetes, are of enormous importance in the context of present-day human health and welfare. Extensive research is therefore being carried out to define the molecular details of the mechanism of the pathological conversion of amyloidogenic proteins from their soluble forms into fibrillar structures. This review focuses on recent studies that demonstrate the power of using antibodies or antibody fragments to probe the process of fibril formation, and discusses the emerging potential of these species as diagnostic and therapeutic agents. [less ▲]

Detailed reference viewed: 18 (1 ULg)