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Engineering a camelid antibody fragment that binds to the active site of human lysozyme and inhibits its conversion into amyloid fibrils

Chan, P.H. and Pardon, E. and Menzer, L. and de Genst, E. and Kumita, J.R. and Christodoulou, John and Saerens, D. and Brans, A. and Bouillenne, F. and Archer, D.B. and Robinson, C.V. and Muyldermans, S. and Matagne, A. and Redfield, C. and Wyns, L. and Dobson, C.M. and Demoulin, M. (2008) Engineering a camelid antibody fragment that binds to the active site of human lysozyme and inhibits its conversion into amyloid fibrils. Biochemistry 47 (42), pp. 11041-11054. ISSN 0006-2960.

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Official URL: http://dx.doi.org/10.1021/bi8005797

Abstract

A single-domain fragment, cAb-HuL22, of a camelid heavy-chain antibody specific for the active site of human lysozyme has been generated, and its effects on the properties of the I56T and D67H amyloidogenic variants of human lysozyme, which are associated with a form of systemic amyloidosis, have been investigated by a wide range of biophysical techniques. Pulse-labeling hydrogen−deuterium exchange experiments monitored by mass spectrometry reveal that binding of the antibody fragment strongly inhibits the locally cooperative unfolding of the I56T and D67H variants and restores their global cooperativity to that characteristic of the wild-type protein. The antibody fragment was, however, not stable enough under the conditions used to explore its ability to perturb the aggregation behavior of the lysozyme amyloidogenic variants. We therefore engineered a more stable version of cAb-HuL22 by adding a disulfide bridge between the two β-sheets in the hydrophobic core of the protein. The binding of this engineered antibody fragment to the amyloidogenic variants of lysozyme inhibited their aggregation into fibrils. These findings support the premise that the reduction in global cooperativity caused by the pathogenic mutations in the lysozyme gene is the determining feature underlying their amyloidogenicity. These observations indicate further that molecular targeting of enzyme active sites, and of protein binding sites in general, is an effective strategy for inhibiting or preventing the aberrant self-assembly process that is often a consequence of protein mutation and the origin of pathogenicity. Moreover, this work further demonstrates the unique properties of camelid single-domain antibody fragments as structural probes for studying the mechanism of aggregation and as potential inhibitors of fibril formation.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 04 Aug 2010 14:09
Last Modified: 17 Apr 2013 12:17
URI: http://eprints.bbk.ac.uk/id/eprint/1006

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