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Publication Abstract from PubMed

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 alpha-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. DeltaY207 and DeltaC-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.

Structural insights into lipid-dependent reversible dimerization of human GLTP.,Samygina VR, Ochoa-Lizarralde B, Popov AN, Cabo-Bilbao A, Goni-de-Cerio F, Molotkovsky JG, Patel DJ, Brown RE, Malinina L Acta Crystallogr D Biol Crystallogr. 2013 Apr;69(Pt 4):603-16. doi:, 10.1107/S0907444913000024. Epub 2013 Mar 14. PMID:23519669^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.