TY - JOUR
T1 - Structural insights into lipid-dependent reversible dimerization of human GLTP
AU - Samygina, Valeria R.
AU - Ochoa-Lizarralde, Borja
AU - Popov, Alexander N.
AU - Cabo-Bilbao, Aintzane
AU - Goni-De-Cerio, Felipe
AU - Molotkovsky, Julian G.
AU - Patel, Dinshaw J.
AU - Brown, Rhoderick E.
AU - Malinina, Lucy
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/4
Y1 - 2013/4
N2 - 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 -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.
AB - 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 -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.
KW - GLTP fold
KW - glycolipid transfer protein
KW - lipid-mediated homodimerization
KW - selectivity
KW - sulfatides
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U2 - 10.1107/S0907444913000024
DO - 10.1107/S0907444913000024
M3 - Article
C2 - 23519669
AN - SCOPUS:84875429646
SN - 0907-4449
VL - 69
SP - 603
EP - 616
JO - Acta Crystallographica Section D: Biological Crystallography
JF - Acta Crystallographica Section D: Biological Crystallography
IS - 4
ER -