Oyvind Halskau

University of Bergen | UiB · Department of Molecular Biology

Lipids have been implicated in Parkinson's Disease (PD). We therefore studied the lipid profile of the neuroblastoma SH-SY5Y cell line, which is used extensively in PD research and compared it to that of the A431 epithelial cancer cell line. We have isolated whole cell extracts (WC) and plasma membrane (PM) fractions of both cell lines. The isolate...

The protein Vitellogenin (Vg) plays a central role in lipid transportation in most egg‐laying animals. High Vg levels correlate with stress resistance and lifespan potential in honey bees (Apis mellifera). Vg is the primary circulating zinc‐carrying protein in honey bees. Zinc is an essential metal ion in numerous biological processes, including th...

Vitellogenin (Vg) is a phylogenetically broad glycolipophosphoprotein. A major function of this protein is holding lipid cargo for storage and transportation. Vg has been extensively studied in honey bees (Apis mellifera) due to additional functions in social traits. Using AlphaFold and EM contour mapping, we recently described the protein structur...

The CW domain binds to histone tail modifications found in different protein families involved in epigenetic regulation and chromatin remodeling. CW domains recognize the methylation state of the fourth lysine on histone 3 and could, therefore, be viewed as a reader of epigenetic information. The specificity toward different methylation states such...

The protein Vitellogenin (Vg) plays a central role in lipid transportation in most egg-laying animals. High Vg levels correlate with stress resistance and lifespan potential in honey bees ( Apis mellifera ). Vg is the primary circulating zinc-carrying protein in honey bees. Zinc is an essential metal ion in numerous biological processes, including...

Vitellogenin (Vg) has been implicated as a central protein in the immunity of egg‐laying animals. Studies on a diverse set of species suggest that Vg supports health and longevity through binding to pathogens. Specific studies of honey bees (Apis mellifera) further indicate that the vitellogenin (vg) gene undergoes selection driven by local pathoge...

The driving forces and conformational pathways leading to amphitropic protein-membrane binding and in some cases also to protein misfolding and aggregation is the subject of intensive research. In this study, a chimeric polypeptide, A-Cage-C, derived from α-Lactalbumin is investigated with the aim of elucidating conformational changes promoting int...

The structural challenges faced by eukaryotic cells through the cell cycle are key for understanding cell viability and proliferation. We tested the hypothesis that the biosynthesis of structural lipids is linked to the cell cycle. If true, this would suggest that the cell's structure is important for progress through and perhaps even control of th...

The structural challenges faced by eukaryotic cells through the cell cycle are key for understanding cell viability and proliferation. In this study, we tested the hypothesis that the biosynthesis of structural lipids is linked to the cell cycle. If true, this would suggest that the cell's structure would form part the control of the cell cycle. Li...

Exosomes are vesicles involved in intercellular communication. Their membrane structure and core content is largely dependent on the cell of origin. Exosomes have been investigated both for their biological roles and their possible use as disease biomarkers and drug carriers. These potential technological applications require the rigorous character...

Dysregulation of the biosynthesis of cholesterol and other lipids has been implicated in many neurological diseases, including Parkinson's disease. Misfolding of α‐Synuclein (α‐Syn), the main actor in Parkinson's, is associated with changes in a lipid environment. However, the exact molecular mechanisms underlying cholesterol effect on α‐Syn bindin...

Exosomes are vesicles involved in intercellular communication. Their membrane structure and core content is largely dependent on the cell of origin. Exosomes have been investigated both for their biological roles and their possible use as disease biomarkers and drug carriers. These potential technological applications require the rigorous character...

Chromatin post-translational modifications are thought to be important for epigenetic effects on gene expression. Methylation of histone N-terminal tail lysine residues constitutes one of many such modifications, executed by families of Histone Lysine Methyltransferase (HKMTase). One such protein is ASHH2 from the flowering plant Arabidopsis thalia...

Marine sponges and soft corals have yielded novel compounds with antineoplastic and antimicrobial activities. Their mechanisms of action are poorly understood, and in most cases, little relevant experimental evidence is available on this topic. In the present study, we investigated whether agelasine D (compound 1) and three agelasine analogs (compo...

Global lipid analysis still lags behind proteomics with respect to the availability of databases, experimental protocols, and specialized software. Determining the lipidome of cellular model systems in common use is of particular importance, especially when research questions involve lipids directly. In Parkinson’s disease research, there is a grow...

Phospholipid quantification by ³¹P NMR and lipid separation and detection by LC-MS/MS. Fatty acid quantification using scripted reconstruction of elution profile for each fatty acid associated with each lipid species. The combination of NMR and and MS data is complementary and allows better quantification and more complete description th...

Abstract Doxorubicin and paclitaxel, two hydrophobic chemotherapeutic agents, are used in cancer therapies. Presence of hydrophobic patches and a flexible fold could probably make α-Lactalbumin a suitable carrier for hydrophobic drugs. In the present study, a variety of thermodynamic, spectroscopic, computational, and cellular techniques were appli...

The ASHH2 CW domain is responsible for recognizing the methylation state at lysine 4 of histone 3 N-terminal tails and implicated in the recruitment of the ASHH2 methyltransferase enzyme correctly to the histones. The ASHH2 CW domain binds H3 lysine motifs that can be either mono-, di-, or tri-methylated [ARTK(meX)QTAR, where X denotes the number o...

This paper reports that the abundances of endogenous cardiolipin and phosphatidylethanolamine halve during elongation of the Gram-positive bacterium Listeria innocua. The lyotropic phase behaviour of model lipid systems that describe these modulations in lipid composition indicate that the average stored curvature elastic stress of the membrane is...

This article is related to http://dx.doi.org/10.1016/j.bbamem.2017.01.005 [1]. In protein and polypeptide-membrane interaction studies, negatively charged lipids are often used as they are a known driver for membrane interaction. When using fluorescence spectroscopy and CD as indicators of polypeptide binding and conformational change, respectively...

Helix A and -C of α-Lactalbumin, a loosely folded amphitropic protein, perturb lipid monolayers by the formation of amyloid pore-like structures. To investigate whether these helices are able to disrupt fully formed bilayers, we designed peptides comprised of Helix A and -C, and investigated their membrane-perturbing properties. The peptides, desig...

Neurodegenerative Protein Misfolding Diseases (PMDs), such as Alzheimer's (AD), Parkinson's (PD) and prion diseases, are generally difficult to diagnose before irreversible damage to the central nervous system damage has occurred. Detection of the misfolded proteins that ultimately lead to these conditions offers a means for providing early detecti...

Human α-lactalbumin made lethal to tumor cells (HAMLET) is a tumoricidal complex consisting of human α-lactalbumin and multiple oleic acids (OAs). OA has been shown to play a key role in the activity of HAMLET and its related complexes, generally known as protein–fatty acid (PFA) complexes. In contrast to what is known about the fate of the protein...

Mammalian 14-3-3 protein scaffolds include seven conserved isoforms that bind numerous phosphorylated protein partners and regulate many cellular processes. Some 14-3-3-isoforms, notably c, have elevated affinity for membranes, which might contribute to modulate the subcellular localization of the partners and substantiate the importance of investi...

Neutrophil serine proteases Proteinase 3 (PR3) and human neutrophil elastase (HNE) are homologous antibiotic serine proteases of the polymorphonuclear neutrophils. Despite sharing a 56% sequence identity they have been shown to have different functions and localizations in the neutrophils. In particular, and in contrast to HNE, PR3 has been detecte...

Tyrosine hydroxylase (TH) catalyzes the rate limiting step in the synthesis of catecholamine neutrotransmitters, and a reduction of TH activity is associated with several neurological diseases. Human TH is regulated, among other mechanisms, by Ser19-phosphorylation-dependent interaction with 14-3-3 proteins. The N-terminal sequence (residues 1-43),...

HAMLET/BAMLET (Human/Bovine α-Lactalbumin Made Lethal to Tumors) is a tumoricidal substance composed of partially unfolded human/bovine α-lactalbumin (HLA/BLA) and several oleic acid (OA) molecules. The HAMLET mechanism of interaction involves an insufficiently understood effect on the membrane or its embedded components. We examined the effect of...

Large lipid transfer proteins are involved in lipid transportation and diverse other molecular processes. These serum proteins include vitellogenins, which are egg yolk precursors and pathogen pattern recognition receptors, and apolipoprotein B, which is an anti-inflammatory cholesterol carrier. In the honey bee, vitellogenin acts as an antioxidant...

Human α-Lactalbumin made lethal to tumor cells (HAMLET), and its bovine analogue BAMLET, have in the recent years shown promising results in cancer therapy. HAMLET contains several oleic acids which in turn stabilize a partially unfolded conformational state of the protein, inducing a higher surface activity compared to the native protein, and like...

Protein-stabilized gold nanoconstructs are widely studied due to their potential applications in biosensing, drug and gene delivery, and bioimaging. While a number of studies have focused on the novel properties of such materials emanating from the gold, there has been little focus on how the protein shell is affected by nanocluster formation with...

Mammalian 14-3-3 protein scaffolds include seven conserved isoforms that bind numerous phosphorylated protein partners and regulate many cellular processes. Some 14-3-3-isoforms, notably c, have elevated affinity for membranes, which might contribute to modulate the subcellular localization of the partners and substantiate the importance of investi...

Circular dichroism (CD) of 14-3-3γ and d14-3-3γ; effect of Na-phosphate. A) Far-UV CD spectrum of 14-3-3γ (7 µM subunit) in 50 mM Na-phosphate, pH 7.4, 150 mM NaCl (black line), d14-3-3γ, after dialysis in 10 mM Na-Hepes, pH 7.4 (blue line) and d14-3-3γ in the presence of 159 mM Na-phosphate (red line). B) CD-monitored thermal denaturation of d14-3...

Comparison of positional fluctuations. The upper panel shows the theoretical positional fluctuations obtained from molecular dynamics simulations along 14-3-3γ-holo (black bars) and 14-3-3γ-apo (red lines); same as main Figure 4B. Helices are indicated schematically as black stripes. The lower panel shows the experimentally obtained beta factors (P...

Electrostatic potential of 14-3-3 along molecular dynamics (MD) simulations. The electrostatic potential of representative snapshots obtained from the MD simulations of 14-3-3γ (rows 1–2), 14-3-3ζ (rows 3–4), and H158F/H195S-14-3-3γ (row 5) are visualized on the solvent accessible, convex surface, oriented to visualize the dimerization domain. Valu...

Dimeric structure obtained at the end of the MD simulation (100 ns) of holo-14-3-3γ. See main text for details. (PDB)

31Phosphate-NMR. Spectra of non-dialyzed 14-3-3γ prepared in 10 mM citric acid/Na-citrate buffer, pH 7.3 (red trace). The sample had a 14-3-3 dimer concentration of 0.7 mM, and 5% D2O was added to the sample. 31P NMR was performed at 25°C on a 500 MHz DRX Bruker instrument using a receiver gain of 5 160.6 and accumulating 32 000 transients. The dat...

Dimeric structure obtained at the end of the MD simulations (100 ns) of apo-14-3-3γ. See main text for details. (PDB)

The structure of 14-3-3γ and sequence diversity in the 14-3-3 family. Top) The structure of 14-3-3γ with a phosphoserine (pSer, in red) peptide (RAIpSLP) bound in the concave cavity of each subunit. The dimeric structure of the protein (PDB 2B05) is shown in backbone ribbon (subunit A) and surface representation (subunit B). Down) Sequence alignmen...

Model of the predicted orientation of ligand-bound 14-3-3γ for optimal interaction with negatively charged membranes. The protein has a positive surface electrostatic potential at the N-terminal dimerization region especially in the presence of bound phosphopeptide (Figure 4), which gives the acidic protein adequate properties for membrane interact...

pH dependency of the electrostatic potential at the convex side. The electrostatic potential is shown at pH values 7.0, 6.5, 6.0 and 5.5 (column wise) for 14-3-3γ (A), 14-3-3ζ (B), and H158F/H195S-14-3-3γ (C). (TIF)

The human immunodeficiency virus type 1 (HIV-1) p6 protein has recently been recognized as a docking site for several cellular and viral binding partners and is important for the formation of infectious viruses. Most of its known functions are suggested to occur under hydrophobic conditions near the cytoplasmic membrane, where the protein is presum...

Small noble metal nanoclusters can be formed in situ by direct reduction and stabilization of a metal precursor by biomolecules such as proteins. Considering the diversity in amino acid composition of proteins, and hence their reductive ability, a general method for synthesis of gold nanoclusters using proteins is presented here. A range of protein...

Vitellogenin (Vg) is an egg-yolk precursor protein in most oviparous species. In honeybee (Apis mellifera), the protein (AmVg) also affects social behavior and life-span plasticity. Despite its manifold functions, the AmVg molecule remains poorly understood. The subject of our structure-oriented AmVg study is its polyserine tract - a little-investi...

Recently, the anticancer activity of human α-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine α-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oli...

Proteinase 3 (PR3) is a serine protease of the neutrophils involved in inflammation processes. Its membrane expression is a risk factor for chronic inflammatory diseases. Experimental data led to divergent hypotheses on the binding mode of PR3 to the plasma membrane of neutrophils. While several studies performed on cell lines have identified a num...

In this issue of Molecular Ecology, Kent et al. (2011) describe the adaptive evolution of honey bee vitellogenin that belongs to a phylogenetically conserved group of egg yolk precursors. This glyco-lipoprotein leads a double life: it is central to egg production in the reproductive queen caste, and a regulator of social behaviour in the sterile wo...

Binding to colloidal structures such as gold nanoparticles (Aunps) is known to affect protein conformation, potentially altering the function and bioinvasiveness of the biopolymer. As the use of protein–Aunp constructs is widespread and increasing, an improved understanding of the invasiveness of nanomaterials is of fundamental interest and crucial...

Human 14-3-3 proteins contain two conserved tryptophan residues in each monomer, Trp60 and Trp233 in isoform γ. 14-3-3γ binds to negatively charged membranes and here we show that membrane binding can be monitored by steady-state intrinsic fluorescence spectroscopy. Measurements with W60F and W233F 14-3-3γ mutants revealed that Trp60 is the major c...

Vitellogenin, an egg-yolk protein precursor common to oviparous animals, is found abundantly in honeybee workers - a caste of helpers that do not usually lay eggs. Instead, honeybee vitellogenin (180 kDa) participates in processes other than reproduction: it influences hormone signaling, food-related behavior, immunity, stress resistance and longev...

By adsorbing bovine serum albumin (BSA) on gold nanoparticles (Aunps) with diameters 30 nm and 80 nm, different degrees of protein unfolding were obtained. Adsorption and adlayer conformation were characterized by UV-vis spectroscopy, ζ-potential measurements, steady-state and time-resolved fluorescence. The unfolding was also studied using 1-anili...

Interaction of cytochrome c (Cyt c), α-lactalbumin III (α-La III) with Langmuir monolayers of pure and mixed glycerophospholipids was investigated using surface pressure-area (Π-A) isotherms. The general trend was that maximum interaction between protein and phospholipid is observed for mixed (1:1 molar ratio) phospholipid monolayers. Interaction b...

Tyrosine hydroxylase is studied in terms of adsorption behaviour on gold surfaces and various passivating layers. Results reveal differences in layer formation, where mercaptoundecanoic acid-coated gold shows the best potential in terms of adsorbed mass. Nanoparticles with this coating are subsequently tested for enzymatic activity, which remains a...

Cell membrane interactions rely on lipid bilayer constituents and molecules inserted within the membrane, including specific receptors. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a tumoricidal complex of partially unfolded alpha-lactalbumin (HLA) and oleic acid that is internalized by tumor cells, suggesting that interactions wi...

Amphitrophic proteins are soluble, globular proteins that may - under certain conditions - interact reversibly with a plasma membrane. How this apparent duality in the properties of a protein is achieved has been a relatively little-studied subject until recently. In this review we aim to summarize the current knowledge regarding some important amp...

Tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamines, is activated by phosphorylation-dependent binding to 14-3-3 proteins. The N-terminal domain of TH is also involved in interaction with lipid membranes. We investigated the binding of the N-terminal domain to its different partners, both in the unphosphorylated (...

For studies of protein-lipid interactions, thin films at the air-water surface are often employed as model systems for cell membranes. A convenient manner in which to study these interactions is the Langmuir technique, which allows for formation of monolayer phospholipid films together with a choice of where and how to introduce proteins, according...

Thermophiles, mesophiles, and psychrophiles have different amino acid frequencies in their proteins, probably because of the way the species adapt to very different temperatures in their environment. In this paper, we analyse how contacts between sidechains vary between homologous proteins from species that are adapted to different temperatures, bu...

Protein folding barriers, which range from zero to the tens of RT that result in classical two-state kinetics, are primarily determined by protein size and structural topology [Plaxco KW, Simons KT, Baker D (1998) J Mol Biol 277:985–994]. Here, we investigate the thermodynamic folding barriers of two relatively large proteins of the same size and t...

The adsorption of eight different proteins (alpha-lactalbumin (types I and III), bovine serum albumin, hemoglobin, myoglobin, cytochrome c, alpha-casein, and lysozyme) onto a model anionic surface was performed at equivalent bulk (solvent, ionic strength, pH) and surface conditions. Adsorption was monitored on a quartz crystal microbalance with dis...

We studied the amino acid frequency and substitution patterns between homologues of prokaryotic species adapted to temperatures in the range 0-102 degrees C, and found a significant temperature-dependent difference in frequency for many of the amino acids. This was particularly clear when we analysed the surface and core residues separately. The di...

Several studies have shown that the physical state of the phospholipid membrane has an important role in protein-membrane interactions, involving both electrostatic and hydrophobic forces. We have investigated the influence of the interaction of the calcium-depleted, (apo)-conformation of bovine alpha-lactalbumin (BLA) on the integrity of anionic g...