Structural insights into lipid-dependent reversible dimerization of human GLTP
| Autor: | Borja Ochoa-Lizarralde, Lucy Malinina, V. R. Samygina, Aintzane Cabo-Bilbao, Julian G. Molotkovsky, Rhoderick E. Brown, Alexander Popov, Felipe Goni-de-Cerio, Dinshaw J. Patel |
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| Rok vydání: | 2013 |
| Předmět: |
Protein Folding
Stereochemistry Dimer Mutant Crystal structure Crystallography X-Ray Ligands Glycosphingolipids Protein Structure Secondary Structure-Activity Relationship 03 medical and health sciences chemistry.chemical_compound Glycolipid Structural Biology Humans glycolipid transfer protein Lipid Transport 030304 developmental biology 0303 health sciences biology Sphingosine Chemistry 030302 biochemistry & molecular biology selectivity Glycolipid binding General Medicine Lipid Metabolism Research Papers Glycolipid transfer protein sulfatides lipid-mediated homodimerization biology.protein lipids (amino acids peptides and proteins) Protein Multimerization Carrier Proteins GLTP fold Protein Binding |
| Zdroj: | Acta Crystallographica Section D: Biological Crystallography |
| ISSN: | 1399-0047 0907-4449 |
| Popis: | It is shown that dimerization is promoted by glycolipid binding to human GLTP. The importance of dimer flexibility in wild-type protein is manifested by point mutation that ‘locks’ the dimer while diversifying ligand/protein adaptations. Human glycolipid transfer protein (hsGLTP) forms the prototypical GLTP fold and is characterized by a broad transfer selectivity for glycosphingolipids (GSLs). The GLTP mutation D48V near the ‘portal entrance’ of the glycolipid binding site has recently been shown to enhance selectivity for sulfatides (SFs) containing a long acyl chain. Here, nine novel crystal structures of hsGLTP and the SF-selective mutant complexed with short-acyl-chain monoSF and diSF in different crystal forms are reported in order to elucidate the potential functional roles of lipid-mediated homodimerization. In all crystal forms, the hsGLTP–SF complexes displayed homodimeric structures supported by similarly organized intermolecular interactions. The dimerization interface always involved the lipid sphingosine chain, the protein C-terminus (C-end) and α-helices 6 and 2, but the D48V mutant displayed a ‘locked’ dimer conformation compared with the hinge-like flexibility of wild-type dimers. Differences in contact angles, areas and residues at the dimer interfaces in the ‘flexible’ and ‘locked’ dimers revealed a potentially important role of the dimeric structure in the C-end conformation of hsGLTP and in the precise positioning of the key residue of the glycolipid recognition centre, His140. ΔY207 and ΔC-end deletion mutants, in which the C-end is shifted or truncated, showed an almost complete loss of transfer activity. The new structural insights suggest that ligand-dependent reversible dimerization plays a role in the function of human GLTP. |
| Databáze: | OpenAIRE |
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