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Ligand binding to pentraxins

Ligand binding to pentraxins
Ligand binding to pentraxins

The human pentraxin proteins, serum amyloid P component (SAP) and C-reactive protein (CRP) have emerged as potentially important targets in the treatment of amyloidosis and cardiovascular diseases respectively, although their normal physiological functions are unclear. Structurally highly conserved homologous proteins are present in common experimental animals such as the rat, mouse, rabbit and hamster but there are major differences from the human pentraxins in their normal behaviour as acute phase proteins, fine ligand specificity and capacity to activate the complement system.

SAP binds to amyloid fibrils of all types and may contribute to their formation, stabilisation and persistence. In order to extend our current knowledge of ligand recognition by SAP, the crystal structures of SAP complexed to two ligands, Methylmalonic acid and Phosphatidylethanolamine, have been solved to 1.6 A and 1.4 A resolution respectively. 

Since important biological functions of proteins are often conserved among species, the structural differences between the rat and human pentraxins were investigated. The crystal structure of rat SAP was solved to 2.2 A resolution by molecular replacement. This pentameric structure displayed subtle differences in the electrostatic properties. It remains to be determined whether this has an effect on avid binding of SAP to DNA, a functional property of human SAP still poorly understood. 

CRP, a pentraxin traditionally defined by its binding affinity for PC, was studied in complex with PE. The crystal structure of the CRP-PE complex at 2.7 A resolution revealed that the nitrogen end of PE dips further downwards into the hydrophobic pocket of CRP than PC. 

CRP-mediated complement activation can exacerbate ischemic tissue injury in the heart as well as in the brain. Therefore, knowledge of the exact stoichiometry and the protein-protein interactions between CRP and Clq may aid the development of small molecules capable of disrupting such protein-protein interactions. Purification of Clq has been achieved by ion-exchange chromatography and gel filtration from BPL paste. Crystallisation trials have been performed, however no crystals have been observed that contain the protein-protein complex.

University of Southampton
Mikolajek, Halina
620c7a94-cf21-4650-be3d-8a628835e2d2
Mikolajek, Halina
620c7a94-cf21-4650-be3d-8a628835e2d2

Mikolajek, Halina (2008) Ligand binding to pentraxins. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The human pentraxin proteins, serum amyloid P component (SAP) and C-reactive protein (CRP) have emerged as potentially important targets in the treatment of amyloidosis and cardiovascular diseases respectively, although their normal physiological functions are unclear. Structurally highly conserved homologous proteins are present in common experimental animals such as the rat, mouse, rabbit and hamster but there are major differences from the human pentraxins in their normal behaviour as acute phase proteins, fine ligand specificity and capacity to activate the complement system.

SAP binds to amyloid fibrils of all types and may contribute to their formation, stabilisation and persistence. In order to extend our current knowledge of ligand recognition by SAP, the crystal structures of SAP complexed to two ligands, Methylmalonic acid and Phosphatidylethanolamine, have been solved to 1.6 A and 1.4 A resolution respectively. 

Since important biological functions of proteins are often conserved among species, the structural differences between the rat and human pentraxins were investigated. The crystal structure of rat SAP was solved to 2.2 A resolution by molecular replacement. This pentameric structure displayed subtle differences in the electrostatic properties. It remains to be determined whether this has an effect on avid binding of SAP to DNA, a functional property of human SAP still poorly understood. 

CRP, a pentraxin traditionally defined by its binding affinity for PC, was studied in complex with PE. The crystal structure of the CRP-PE complex at 2.7 A resolution revealed that the nitrogen end of PE dips further downwards into the hydrophobic pocket of CRP than PC. 

CRP-mediated complement activation can exacerbate ischemic tissue injury in the heart as well as in the brain. Therefore, knowledge of the exact stoichiometry and the protein-protein interactions between CRP and Clq may aid the development of small molecules capable of disrupting such protein-protein interactions. Purification of Clq has been achieved by ion-exchange chromatography and gel filtration from BPL paste. Crystallisation trials have been performed, however no crystals have been observed that contain the protein-protein complex.

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Published date: 2008

Identifiers

Local EPrints ID: 466494
URI: http://eprints.soton.ac.uk/id/eprint/466494
PURE UUID: 015070e0-6093-481b-a3c4-994f216bbe26

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Date deposited: 05 Jul 2022 05:22
Last modified: 16 Mar 2024 20:44

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Author: Halina Mikolajek

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