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Leonard J. Banaszak - One of the best experts on this subject based on the ideXlab platform.
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Lipid-protein interactions in Lipovitellin.
Biochemistry, 2002Co-Authors: James R. Thompson, Leonard J. BanaszakAbstract:The refined molecular structure of Lipovitellin is described using synchrotron cryocrystallographic data to 1.9 A resolution. Lipovitellin is the predominant lipoprotein found in the yolk of egg-laying animals and is involved in lipid and metal storage. It is thought to be related in amino acid sequence to segments of apolipoprotein B and the microsomal transfer protein responsible for the assembly of low-density lipoproteins. Lipovitellin contains a heterogeneous mixture of about 16% (w/w) noncovalently bound lipid, mostly phospholipid. Previous X-ray structural studies at ambient temperature described several different protein domains including a large cavity in each subunit of the dimeric protein. The cavity was free of any visible electron density for lipid molecules at room temperature, suggesting that only dynamic interactions exist with the protein. An important result from this crystallographic study at 100 K is the appearance of some bound ordered lipid along the walls of the binding cavity. The precise identification of the lipid type is difficult because of discontinuities in the electron density. Nonetheless, the conformations of 7 phospholipids and 43 segments of hydrocarbon chains greater than 5 atoms in length have been discovered. The conformations of the bound lipid and the interactions between protein and lipid provide insights into the factors governing lipoprotein formation.
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The structural basis of lipid interactions in Lipovitellin, a soluble lipoprotein
Structure (London England : 1993), 1998Co-Authors: Timothy A. Anderson, David G. Levitt, Leonard J. BanaszakAbstract:Abstract Background: The conformation and assembly of lipoproteins, proteins containing large amounts of noncovalently bound lipid, is poorly understood. Lipoproteins present an unusual challenge as they often contain varying loads of lipid and are not readily crystallized. Lipovitellin is a large crystallizable oocyte protein of approximately 1300 residues that contains about 16% w/w lipid. Lipovitellin contains two large domains that appear to be conserved in both microsomal triglyceride transfer protein and apolipoprotein B-100. To gain insight into the conformation of a lipoprotein and the potential modes of binding of both neutral and phospholipid, the crystal structure of lamprey Lipovitellin has been determined. Results: We report here the refined crystal structure of Lipovitellin at 2.8 a resolution. The structure contains 1129 amino acid residues located on five peptide chains, one 40-atom phosphatidylcholine, and one 13-atom hydrocarbon chain. The protein contains a funnel-shaped cavity formed primarily by two β sheets and lined predominantly by hydrophobic residues. Conclusions: Using the crystal structure as a template, a model for the bound lipid is proposed. The lipid-binding cavity is formed primarily by a single-thickness β -sheet structure which is stabilized by bound lipid. This cavity appears to be flexible, allowing lipid to be loaded or unloaded.
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Sequence of lamprey vitellogenin. Implications for the Lipovitellin crystal structure.
Journal of molecular biology, 1992Co-Authors: William J. Sharrock, Tamzin A. Rosenwasser, Janet Gould, Julie A. Knott, Deborah M. Hussey, Jeffrey I. Gordon, Leonard J. BanaszakAbstract:The amino acid sequence of lamprey vitellogenin has been predicted from the nucleotide sequence of cloned cDNA. The sites of proteolytic cleavage that produce the Lipovitellin complex from the vitellogenin have been located by comparing the N-terminal sequences of two lamprey Lipovitellin polypeptides with the predicted sequence. These results also confirm that the vitellogenin sequence derived here corresponds to the Lipovitellin complex for which the crystal structure has been solved previously. Predictions of secondary structure indicate that the region most likely to correspond to the large α-helical domain of the crystallographic model consists of vitellogenin residues 300 to 600. Similar to the Lipovitellins of Xenopus laevis, lamprey Lipovitellin appears to lack approximately 200 C-terminal residues that are present in vitellogenin. However, the lamprey Lipovitellin differs from those of Xenopus and chicken in two respects. First, most of the serine-rich domain that is present as the phosvitin polypeptide in the Lipovitellins of the higher vertebrates appears to be lost in the maturation of lamprey vitellogenin to Lipovitellin. Second, the domains that constitute the large Lipovitellin-1 polypeptide in Xenopus and chicken are present in two polypeptides in lamprey, owing to an additional proteolytic processing event.
Marja T. Hyvönen - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics simulations of a Lipovitellin derived amphiphilic β sheet homologous to apob 100 β sheets at a hydrophobic decane water interface
Biochimica et Biophysica Acta, 2008Co-Authors: Artturi Koivuniemi, Petri T. Kovanen, Marja T. HyvönenAbstract:Abstract Lipovitellin, an egg-yolk lipoprotein, transports lipids in a pocket surrounded by amphiphilic β-sheets. Its X-ray structure provides possibilities to study interactions between lipophilic β-sheets and lipids at the atomic level. Here, we studied a 67-residue-long amphiphilic β-sheet of Lipovitellin previously suggested a suitable working model for studies of the lipid-binding behaviour of amphiphilic β-sheet regions in apolipoprotein B-100 (apoB-100). We performed four molecular dynamics simulations with different starting configurations to define characteristics of the amphiphilic β-sheet model at a decane–water interface. In each simulation the model β-sheet bound keenly to the decane layer via its hydrophobic surface. The structural profiles showed unchanged secondary structure of the β-sheet during the attachment. Also, aromatic side chains, especially tryptophans and tyrosines, mediated the attachment to the hydrophobic layer and influenced the orientation of the decane molecules that are in contact with the β-sheet. In conclusion, the present simulations reveal high affinity of a Lipovitellin-derived amphiphilic β-sheet to a hydrophobic decane layer. They lay thereby the basis for further studies of the interaction between amphiphilic β-sheets and lipids in complex molecular systems, like LDL particles, in which the large apoB-100 is the main protein component.
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Molecular dynamics simulations of a Lipovitellin-derived amphiphilic β-sheet homologous to apoB-100 β-sheets at a hydrophobic decane–water interface
Biochimica et biophysica acta, 2008Co-Authors: Artturi Koivuniemi, Petri T. Kovanen, Marja T. HyvönenAbstract:Abstract Lipovitellin, an egg-yolk lipoprotein, transports lipids in a pocket surrounded by amphiphilic β-sheets. Its X-ray structure provides possibilities to study interactions between lipophilic β-sheets and lipids at the atomic level. Here, we studied a 67-residue-long amphiphilic β-sheet of Lipovitellin previously suggested a suitable working model for studies of the lipid-binding behaviour of amphiphilic β-sheet regions in apolipoprotein B-100 (apoB-100). We performed four molecular dynamics simulations with different starting configurations to define characteristics of the amphiphilic β-sheet model at a decane–water interface. In each simulation the model β-sheet bound keenly to the decane layer via its hydrophobic surface. The structural profiles showed unchanged secondary structure of the β-sheet during the attachment. Also, aromatic side chains, especially tryptophans and tyrosines, mediated the attachment to the hydrophobic layer and influenced the orientation of the decane molecules that are in contact with the β-sheet. In conclusion, the present simulations reveal high affinity of a Lipovitellin-derived amphiphilic β-sheet to a hydrophobic decane layer. They lay thereby the basis for further studies of the interaction between amphiphilic β-sheets and lipids in complex molecular systems, like LDL particles, in which the large apoB-100 is the main protein component.
Nassrin Dashti - One of the best experts on this subject based on the ideXlab platform.
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n terminal domain of apolipoprotein b has structural homology to Lipovitellin and microsomal triglyceride transfer protein a lipid pocket model for self assembly of apob containing lipoprotein particles
Journal of Lipid Research, 1999Co-Authors: Jere P. Segrest, Martin K. Jones, Nassrin DashtiAbstract:The process of assembly of apolipoprotein (apo) B-containing lipoprotein particles occurs co-translationally after disulfide-dependent folding of the N-terminal domain of apoB but the mechanism is not understood. During a recent database search for protein sequences that contained similar amphipathic beta strands to apoB-100, four vitellogenins, the precursor form of Lipovitellin, an egg yolk lipoprotein, from chicken, frog, lamprey, and C. elegans appeared on the list of candidate proteins. The X-ray crystal structure of lamprey Lipovitellin is known to contain a "lipid pocket" lined by antiparallel amphipathic beta sheets. Here we report that the first 1000 residues of human apoB-100 (the alpha(1) domain plus the first 200 residues of the beta(1) domain) have sequence and amphipathic motif homologies to the lipid-binding pocket of lamprey Lipovitellin. We also show that most of the alpha(1) domain of human apoB-100 has sequence and amphipathic motif homologies to human microsomal triglyceride transfer protein (MTP), a protein required for assembly of apoB-containing lipoproteins. Based upon these results, we suggest that an LV-like "proteolipid" intermediate containing a "lipid pocket" is formed by the N-terminal portion of apoB alone or, more likely, as a complex with MTP. This intermediate produces a lipid nidus required for assembly of apoB-containing lipoprotein particles; pocket expansion through the addition of amphipathic beta strands from the beta(1) domain of apoB results in the formation of a progressively larger high density lipoprotein (HDL)-like, then very low density lipoprotein (VLDL)-like, spheroidal lipoprotein particle.
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N-terminal domain of apolipoprotein B has structural homology to Lipovitellin and microsomal triglyceride transfer protein: a “lipid pocket” model for self-assembly of apoB-containing lipoprotein particles
Journal of lipid research, 1999Co-Authors: Jere P. Segrest, Martin K. Jones, Nassrin DashtiAbstract:The process of assembly of apolipoprotein (apo) B-containing lipoprotein particles occurs co-translationally after disulfide-dependent folding of the N-terminal domain of apoB but the mechanism is not understood. During a recent database search for protein sequences that contained similar amphipathic beta strands to apoB-100, four vitellogenins, the precursor form of Lipovitellin, an egg yolk lipoprotein, from chicken, frog, lamprey, and C. elegans appeared on the list of candidate proteins. The X-ray crystal structure of lamprey Lipovitellin is known to contain a "lipid pocket" lined by antiparallel amphipathic beta sheets. Here we report that the first 1000 residues of human apoB-100 (the alpha(1) domain plus the first 200 residues of the beta(1) domain) have sequence and amphipathic motif homologies to the lipid-binding pocket of lamprey Lipovitellin. We also show that most of the alpha(1) domain of human apoB-100 has sequence and amphipathic motif homologies to human microsomal triglyceride transfer protein (MTP), a protein required for assembly of apoB-containing lipoproteins. Based upon these results, we suggest that an LV-like "proteolipid" intermediate containing a "lipid pocket" is formed by the N-terminal portion of apoB alone or, more likely, as a complex with MTP. This intermediate produces a lipid nidus required for assembly of apoB-containing lipoprotein particles; pocket expansion through the addition of amphipathic beta strands from the beta(1) domain of apoB results in the formation of a progressively larger high density lipoprotein (HDL)-like, then very low density lipoprotein (VLDL)-like, spheroidal lipoprotein particle.
Richard F. Lee - One of the best experts on this subject based on the ideXlab platform.
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Lipid storage in marine zooplankton
Marine Ecology Progress Series, 2006Co-Authors: Richard F. Lee, Wilhelm Hagen, Gerhard KattnerAbstract:Zooplankton storage lipids play an important role during reproduction, food scarcity, ontogeny and diapause, as shown by studies in various oceanic regions. While triacylglycerols, the primary storage lipid of terrestrial animals, are found in almost all zooplankton species, wax esters are the dominant storage lipid in many deep-living and polar zooplankton taxa. Phospholipids and diacylglycerol ethers are the unique storage lipids used by polar euphausiids and pteropods, respectively. In zooplankton with large stores of wax esters, triacylglycerols are more rapidly turned over and used for short-term energy needs, while wax esters serve as long-term energy deposits. Zooplankton groups found in polar, westerlies, upwelling and coastal biomes are characterized by accumulation of large lipid stores. In contrast, zooplankton from the trades/tropical biomes is mainly composed of omnivorous species with only small lipid reserves. Diapausing copepods, which enter deep water after feeding on phytoplankton during spring/summer blooms or at the end of upwelling periods, are characterized by large oil sacs filled with wax esters. The thermal expansion and compressibility of wax esters may allow diapausing copepods and other deep-water zooplankton to be neutrally buoyant in cold deep waters, and they can thus avoid spending energy to remain at these depths. Lipid droplets are often noted in zooplankton ovaries, and a portion of these droplets can be transferred to developing oocytes. In addition to lipid droplets, zooplankton eggs have yolks with Lipovitellin, a lipoprotein with approximately equal amounts of protein and lipid. The Lipovitellin lipid is predominantly phosphatidylcholine, so during reproduction females must convert a portion of their storage lipid into this phospholipid. Developing embryos use their Lipovitellin and lipid droplets for energy and materials until feeding begins. The various functions storage lipids serve during the different life history stages of zooplankton are very complex and still not fully understood and hence offer a multitude of fascinating research perspectives.
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Characterization of Lipovitellin in eggs of the polychaete Neanthes arenaceodentata.
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2005Co-Authors: Richard F. Lee, Anna N. Walker, Donald J. ReishAbstract:The ooplasm of mature oocytes of the polychaete Neanthes arenaceodentata is characteristically filled with yolk platelets. A major component of these structures is Lipovitellin, which provides energy and materials required by newly hatched larvae. The Lipovitellin isolated and purified from the fertilized eggs of this polychaete was a high-density lipoprotein composed of protein (57%), lipid (42%) and carbohydrate (1%). The lipid component included phospholipids (92% of lipid), triacylglycerol (3% of lipid) and cholesterol (3% of lipid), while sodium dodecyl sulfate-gel electrophoresis showed the major protein component was a 120-kDa peptide. Microscopically, mature oocytes were present in the coelom along with phagocytic eleocytes. The presence of muscle fragments and oil droplets in eleocytes suggests that eleocytes play an important role in providing the protein and lipid needed for the assembly of Lipovitellin in the oocytes.
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Lipovitellin and lipid droplet accumulation in oocytes during ovarian maturation in the blue crab, Callinectes sapidus
Journal of Experimental Zoology, 1995Co-Authors: Richard F. Lee, Anna N. WalkerAbstract:Blue crab ovaries rapidly increased in weight during the 30 days after the terminal molt into adulthood. Oocytes isolated from ovaries during this period increased in diameter from 40 to 201 μm. The concentrations of Lipovitellin, a high density lipoprotein found in oocytes, were determined by a competitive ELISA procedure using a monoclonal antibody against one of the Lipovitellin peptides. Lipovitellin and lipid droplets were minor components in the immature ovaries and oocytes but increased in concentration to become the major components of the mature ovaries and oocytes. In mature oocytes (201 μm diameter) Lipovitellin concentrations accounted for 35 and 95% of the total oocyte protein and soluble oocyte protein, respectively. In mature oocytes the total lipid, Lipovitellin lipid, and lipid droplet concentrations were 510, 240, and 140 ng/oocyte, respectively. Sections of ovaries and hepatopancreas at different stages of maturation were probed with the anti-Lipovitellin antibody. In small immature oocytes, where no yolk was present, the immunoreactivity was confined to perinuclear yolk complexes. The immunoreactivity of more mature oocytes was associated with globular structures in the cytoplasm. Neither ovarian follicle cells nor hepatopancreas cells showed immunoreactivity. Our results suggest that in blue crabs the Lipovitellin components are primarily synthesized in the developing oocytes with perinuclear yolk complexes playing an important role in the formation of Lipovitellin-rich yolk granules. Scattered collections of presumed phagocytic hemocytes contained immunoreactive granular material in their cytoplasm. We suggest that these hemocytes remove debris from oocytes which fail to reach maturation and carry this debris to the hepatopancreas. © 1995 Wiley-Liss, Inc.
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Effect of reproductive toxicants on Lipovitellin in female blue crabs, Callinectes sapidus
Marine Environmental Research, 1995Co-Authors: Richard F. Lee, Thomas NooneAbstract:Abstract Changes in the concentration of Lipovitellin, a lipoprotein that is the major protein in mature oocytes of crustaceans, were determined during ovarian development in female blue crabs, Callinectes sapidus. To test the effects of reproductive toxins on vitellogenesis, crabs were fed food containing cadmium or injected with the juvenile hormone antagonist, precocene II. Monoclonal antibodies prepared against one of the Lipovitellin peptides (peptide A—107 kDa) were used in an enzyme linked immunosorbent assay to determine Lipovitellin concentrations. Recently molted female crabs fed food containing cadmium (0.02 mg/g) for 18 days had oocytes with the same Lipovitellin concentration as controls, but after 24 days the oocytes in cadmium treated crabs had significantly lower lipoprotein contents than controls (30 ± 4 ng/oocyte—cadmium treated; 45 ± 4 ng/oocyte—control). Precocene II-treated crabs had significantiy lower Lipovitellin concentrations after 18 and 24 days. Diameters of oocytes were the same in both treated and control crabs. The results suggest that some pollutants may affect reproduction by acting during secondary vitellogenesis i.e., period when there is a large increase in Lipovitellin synthesis. Since Lipovitellins serve many of the nutritional needs of recently emerged crab embryos, poor larval survival may occur as a result of lower Lipovitellin content.
Artturi Koivuniemi - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics simulations of a Lipovitellin derived amphiphilic β sheet homologous to apob 100 β sheets at a hydrophobic decane water interface
Biochimica et Biophysica Acta, 2008Co-Authors: Artturi Koivuniemi, Petri T. Kovanen, Marja T. HyvönenAbstract:Abstract Lipovitellin, an egg-yolk lipoprotein, transports lipids in a pocket surrounded by amphiphilic β-sheets. Its X-ray structure provides possibilities to study interactions between lipophilic β-sheets and lipids at the atomic level. Here, we studied a 67-residue-long amphiphilic β-sheet of Lipovitellin previously suggested a suitable working model for studies of the lipid-binding behaviour of amphiphilic β-sheet regions in apolipoprotein B-100 (apoB-100). We performed four molecular dynamics simulations with different starting configurations to define characteristics of the amphiphilic β-sheet model at a decane–water interface. In each simulation the model β-sheet bound keenly to the decane layer via its hydrophobic surface. The structural profiles showed unchanged secondary structure of the β-sheet during the attachment. Also, aromatic side chains, especially tryptophans and tyrosines, mediated the attachment to the hydrophobic layer and influenced the orientation of the decane molecules that are in contact with the β-sheet. In conclusion, the present simulations reveal high affinity of a Lipovitellin-derived amphiphilic β-sheet to a hydrophobic decane layer. They lay thereby the basis for further studies of the interaction between amphiphilic β-sheets and lipids in complex molecular systems, like LDL particles, in which the large apoB-100 is the main protein component.
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Molecular dynamics simulations of a Lipovitellin-derived amphiphilic β-sheet homologous to apoB-100 β-sheets at a hydrophobic decane–water interface
Biochimica et biophysica acta, 2008Co-Authors: Artturi Koivuniemi, Petri T. Kovanen, Marja T. HyvönenAbstract:Abstract Lipovitellin, an egg-yolk lipoprotein, transports lipids in a pocket surrounded by amphiphilic β-sheets. Its X-ray structure provides possibilities to study interactions between lipophilic β-sheets and lipids at the atomic level. Here, we studied a 67-residue-long amphiphilic β-sheet of Lipovitellin previously suggested a suitable working model for studies of the lipid-binding behaviour of amphiphilic β-sheet regions in apolipoprotein B-100 (apoB-100). We performed four molecular dynamics simulations with different starting configurations to define characteristics of the amphiphilic β-sheet model at a decane–water interface. In each simulation the model β-sheet bound keenly to the decane layer via its hydrophobic surface. The structural profiles showed unchanged secondary structure of the β-sheet during the attachment. Also, aromatic side chains, especially tryptophans and tyrosines, mediated the attachment to the hydrophobic layer and influenced the orientation of the decane molecules that are in contact with the β-sheet. In conclusion, the present simulations reveal high affinity of a Lipovitellin-derived amphiphilic β-sheet to a hydrophobic decane layer. They lay thereby the basis for further studies of the interaction between amphiphilic β-sheets and lipids in complex molecular systems, like LDL particles, in which the large apoB-100 is the main protein component.