Glycolipid transfer protein: Clear structure and activity, but enigmatic function

Neumann, Sylvia; Opacic, Milena; Wechselberger, Rainer; Sprong, Hein; Egmond, Maarten R.

doi:10.1016/j.advenzreg.2007.11.009

Cited by 15 publications

(14 citation statements)

References 42 publications

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“…Far-UV CD analyses support GLTP fold formation by HET-C2, indicating a preponderance of helical secondary structure as well as a relatively low unfolding transition temperature midpoint (ϳ49°C). Similar features are exhibited by porcine and bovine GLTPs (54,60,61) as well as by human GLTP.…”

Section: Discussionsupporting

confidence: 55%

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Structural Determination and Tryptophan Fluorescence of Heterokaryon Incompatibility C2 Protein (HET-C2), a Fungal Glycolipid Transfer Protein (GLTP), Provide Novel Insights into Glycolipid Specificity and Membrane Interaction by the GLTP Fold

Kenoth

Simanshu

Kamlekar

et al. 2010

Journal of Biological Chemistry

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HET-C2 is a fungal protein that transfers glycosphingolipids between membranes and has limited sequence homology with human glycolipid transfer protein (GLTP). The human GLTP fold is unique among lipid binding/transfer proteins, defining the GLTP superfamily. Herein, GLTP fold formation by HET-C2, its glycolipid transfer specificity, and the functional role(s) of its two Trp residues have been investigated. X-ray diffraction (1.9 Å ) revealed a GLTP fold with all key sugar headgroup recognition residues (Asp 66 , Asn 70 , Lys 73 , Trp 109 , and His 147 ) conserved and properly oriented for glycolipid binding. Far-UV CD showed secondary structure dominated by ␣-helices and a cooperative thermal unfolding transition of 49°C, features consistent with a GLTP fold. Environmentally induced optical activity of Trp/Tyr/Phe (2:4:12) detected by near-UV CD was unaffected by membranes containing glycolipid but was slightly altered by membranes lacking glycolipid. Trp fluorescence was maximal at ϳ355 nm and accessible to aqueous quenchers, indicating free exposure to the aqueous milieu and consistent with surface localization of the two Trps. Interaction with membranes lacking glycolipid triggered significant decreases in Trp emission intensity but lesser than decreases induced by membranes containing glycolipid. Binding of glycolipid (confirmed by electrospray injection mass spectrometry) resulted in a blue-shifted emission wavelength maximum (ϳ6 nm) permitting determination of binding affinities. The unique positioning of Trp 208 at the HET-C2 C terminus revealed membrane-induced conformational changes that precede glycolipid uptake, whereas key differences in residues of the sugar headgroup recognition center accounted for altered glycolipid specificity and suggested evolutionary adaptation for the simpler glycosphingolipid compositions of filamentous fungi.Self/nonself recognition is a universally important process, encompassing intercellular interactions ranging from vertebrate immune responses to somatic chimera formation in protists, filamentous fungi, sponges, ascidians, and tunicates. Self/ nonself discrimination becomes critical for filamentous fungi during hyphal fusion, which enables the exchange of cytoplasm and nuclei during the assimilative growth phase (1-4). Nonself recognition triggers a postfusion, programmed cell death process known as vegetative incompatibility, which leads to heterokaryon death. The benefits of vegetative incompatibility include prevention of transmission of deleterious cytoplasmic elements (i.e. viruses) as well as restriction of plundering by parasitic genotypes.het genes are known to play a major role in vegetative incompatibility processes that occur in Neurospora crassa and Podospora anserina. het genes exhibit extensive polymorphism and generally encode proteins carrying a HET domain (1-4). Originally, this domain was linked to the het-c2 gene of P. anserina, where it was shown to encode a protein similar in size and with limited sequence homology to mammalian glycolipid transfer...

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Section: Discussionsupporting

confidence: 55%

“…The involvement of Trp in GLTP functionality is well established (8,9,45,46,(51)(52)(53)(54)(55) (Fig. 2A).…”

Section: Discussionmentioning

confidence: 99%

Structural Determination and Tryptophan Fluorescence of Heterokaryon Incompatibility C2 Protein (HET-C2), a Fungal Glycolipid Transfer Protein (GLTP), Provide Novel Insights into Glycolipid Specificity and Membrane Interaction by the GLTP Fold

Kenoth

Simanshu

Kamlekar

et al. 2010

Journal of Biological Chemistry

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“…6 In addition, two tryptophan residues (Trp473 and Trp562) have been shown to be important for ceramide extraction and transfer activities. 6 Because tryptophan residues have a high propensity for membrane interactions, 9,10 we speculated that these residues might interact with lipid bilayers when CERT contacts ceramide in the membrane. The different conformation of Trp473 on the Ω1 loop suggests that Trp473 may be important for CERT function.…”

Section: Omega-1 Loop and Trp473 Conformationsmentioning

confidence: 99%

Crystal Structures of the CERT START Domain with Inhibitors Provide Insights into the Mechanism of Ceramide Transfer

Kudo

Kumagai

Matsubara

et al. 2010

Journal of Molecular Biology

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“…In human GLTP, all three reside on or slightly below the surface of the protein where they could potentially help form a membrane-interaction site. There is universal agreement that Trp142, which projects from α-helix6, is involved in the initial docking of GLTP to the membrane (Kamlekar et al 2010; Malinina et al 2004; Neumann et al 2008; Ohvo-Rekilä & Mattjus, 2011; Rao et al 2005; West et al 2006; Zhai et al 2009). The conclusion is based on both experimental and computational modeling that optimize the spatial arrangement of peripheral membrane protein structures with respect to lipid bilayers, i.e.…”

Section: Membrane Interaction and Regulation By Lipid Compositionmentioning

confidence: 99%

Sphingolipid transfer proteins defined by the GLTP-fold

Malinina

Simanshu

Zhai

et al. 2015

Quart. Rev. Biophys.

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Glycolipid transfer proteins (GLTPs) originally were identified as small (~24 kDa), soluble, amphitropic proteins that specifically accelerate the intermembrane transfer of glycolipids. GLTPs and related homologs now are known to adopt a unique, helically dominated, two-layer ‘sandwich’ architecture defined as the GLTP-fold that provides the structural underpinning for the eukaryotic GLTP superfamily. Recent advances now provide exquisite insights into structural features responsible for lipid headgroup selectivity as well as the adaptability of the hydrophobic compartment for accommodating hydrocarbon chains of differing length and unsaturation. A new understanding of the structural versatility and evolutionary premium placed on the GLTP motif has emerged. Human GLTP-motifs have evolved to function not only as glucosylceramide binding/transferring domains for phosphoinositol 4-phosphate adaptor protein-2 during glycosphingolipid biosynthesis but also as selective binding/transfer proteins for ceramide-1-phosphate. The latter, known as ceramide-l-phosphate transfer protein, recently has been shown to form GLTP-fold while critically regulating Group-IV cytoplasmic phospholipase A2 activity and pro-inflammatory eicosanoid production.

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Glycolipid transfer protein: Clear structure and activity, but enigmatic function

Cited by 15 publications

References 42 publications

Structural Determination and Tryptophan Fluorescence of Heterokaryon Incompatibility C2 Protein (HET-C2), a Fungal Glycolipid Transfer Protein (GLTP), Provide Novel Insights into Glycolipid Specificity and Membrane Interaction by the GLTP Fold

Structural Determination and Tryptophan Fluorescence of Heterokaryon Incompatibility C2 Protein (HET-C2), a Fungal Glycolipid Transfer Protein (GLTP), Provide Novel Insights into Glycolipid Specificity and Membrane Interaction by the GLTP Fold

Crystal Structures of the CERT START Domain with Inhibitors Provide Insights into the Mechanism of Ceramide Transfer

Sphingolipid transfer proteins defined by the GLTP-fold

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