Serpins are important regulators of proteolytic pathways with an antiprotease activity that involves a conformational transition from a metastable to a hyperstable state. Certain mutations permit the transition to occur in the absence of a protease; when associated with an intermolecular interaction, this yields linear polymers of hyperstable serpin molecules, which accumulate at the site of synthesis. This is the basis of many pathologies termed the serpinopathies. We have previously identified a monoclonal antibody (mAb4B12) that, in single-chain form, blocks α1-Antitrypsin (α1-AT) polymerisation in cells. Here, we describe the structural basis for this activity. The mAb4B12 epitope was found to encompass residues Glu32, Glu39 and His43 on helix A and Leu306 on helix I. This is not a region typically associated with the serpin mechanism of conformational change, and correspondingly the epitope was present in all tested structural forms of the protein. Antibody binding rendered β-sheet A - on the opposite face of the molecule - more liable to adopt an 'open' state, mediated by changes distal to the breach region and proximal to helix F. The allosteric propagation of induced changes through the molecule was evidenced by an increased rate of peptide incorporation and destabilisation of a preformed serpin-enzyme complex following mAb4B12 binding. These data suggest that prematurely shifting the β-sheet A equilibrium towards the 'open' state out of sequence with other changes suppresses polymer formation. This work identifies a region potentially exploitable for a rational design of ligands that is able to dynamically influence α1-AT polymerisation.

An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behavior / Motamedi Shad, Neda; Jagger, Alistair M.; Liedtke, Maximilian; Faull, Sarah V.; Nanda, Arjun Scott; Salvadori, Enrico; Wort, Joshua L.; Kay, Christopher W. M.; Heyer Chauhan, Narinder; MIRANDA BANOS, MARIA ELENA; Perez, Juan; Ordóñez, Adriana; Haq, Imran; Irving, James A.; Lomas, David A.. - In: BIOCHEMICAL JOURNAL. - ISSN 0264-6021. - STAMPA. - 473:19(2016), pp. 3269-3290. [10.1042/BCJ20160159]

An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behavior

MIRANDA BANOS, MARIA ELENA;
2016

Abstract

Serpins are important regulators of proteolytic pathways with an antiprotease activity that involves a conformational transition from a metastable to a hyperstable state. Certain mutations permit the transition to occur in the absence of a protease; when associated with an intermolecular interaction, this yields linear polymers of hyperstable serpin molecules, which accumulate at the site of synthesis. This is the basis of many pathologies termed the serpinopathies. We have previously identified a monoclonal antibody (mAb4B12) that, in single-chain form, blocks α1-Antitrypsin (α1-AT) polymerisation in cells. Here, we describe the structural basis for this activity. The mAb4B12 epitope was found to encompass residues Glu32, Glu39 and His43 on helix A and Leu306 on helix I. This is not a region typically associated with the serpin mechanism of conformational change, and correspondingly the epitope was present in all tested structural forms of the protein. Antibody binding rendered β-sheet A - on the opposite face of the molecule - more liable to adopt an 'open' state, mediated by changes distal to the breach region and proximal to helix F. The allosteric propagation of induced changes through the molecule was evidenced by an increased rate of peptide incorporation and destabilisation of a preformed serpin-enzyme complex following mAb4B12 binding. These data suggest that prematurely shifting the β-sheet A equilibrium towards the 'open' state out of sequence with other changes suppresses polymer formation. This work identifies a region potentially exploitable for a rational design of ligands that is able to dynamically influence α1-AT polymerisation.
allosteric regulation; antibodies; protein aggregation; protein conformation; protein–protein interactions; serpin; Biochemistry; Molecular Biology; Cell Biology
01 Pubblicazione su rivista::01a Articolo in rivista
An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behavior / Motamedi Shad, Neda; Jagger, Alistair M.; Liedtke, Maximilian; Faull, Sarah V.; Nanda, Arjun Scott; Salvadori, Enrico; Wort, Joshua L.; Kay, Christopher W. M.; Heyer Chauhan, Narinder; MIRANDA BANOS, MARIA ELENA; Perez, Juan; Ordóñez, Adriana; Haq, Imran; Irving, James A.; Lomas, David A.. - In: BIOCHEMICAL JOURNAL. - ISSN 0264-6021. - STAMPA. - 473:19(2016), pp. 3269-3290. [10.1042/BCJ20160159]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/950794
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