Knut Teigen

• PhD
• Professor at University of Bergen

Vesicular monoamine transporter 2 (VMAT2) is responsible for packing monoamine neurotransmitters into synaptic vesicles for storage and subsequent neurotransmission. VMAT2 inhibitors are approved for symptomatic treatment of tardive dyskinesia and Huntington’s chorea, but despite being much-studied inhibitors their exact binding site and mechanism...

Mutant superoxide dismutase 1 (SOD1) may form cyclic structures due to its greater instability from aberrant demetallization and oxidation of cysteine bonds. This cyclic structure may allow SOD1 to form ion channels on membranes such as the mitochondrial membrane, causing imbalances in the concentration of intracellular ions as a potential mechanis...

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of dopamine (DA) and other catecholamines, and its dysfunction leads to DA deficiency and parkinsonisms. Inhibition by catecholamines and reactivation by S40 phosphorylation are key regulatory mechanisms of TH activity and conformational stability. We used Cryo-EM to det...

Background: Clinically, corticosteroids are used mainly for their immune-modulatory properties but are also known to influence mood. Despite evidence of a role in regulating tryptophan hydroxylases (TPHs), key enzymes in serotonin biosynthesis, a direct action of corticosteroids on these enzymes has not been systematically investigated. Methodology...

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...

Tyrosine hydroxylase (TH) catalyses the (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4)-dependent conversion of l-tyrosine to L-3,4-dihydroxyphenylalanine (l-Dopa), which is the rate-limiting step in the synthesis of dopamine and other catecholamine neurotransmitters and hormones. Dysfunctional mutant TH causes tyrosine hydroxylase deficiency (THD...

Serotonin (5-HT) is a hormone and neurotransmitter that modulates neural activity as well as a wide range of other physiological processes including cardiovascular function, bowel motility, and platelet aggregation. 5-HT synthesis is catalyzed by tryptophan hydroxylase (TPH) which exists as two distinct isoforms; TPH1 and TPH2, which are responsibl...

Tyrosine hydroxylase (TH) is a highly regulated enzyme that catalyses the rate-limiting step in the biosynthesis of dopamine (DA) and other catecholamines. Mutations and dysfunction in this enzyme lead to DA deficiency and parkinsonisms of different severity. An understanding of TH deficiency at the level of structure and stability has been lacking...

Aim: Tryptophan hydroxylase 1 (TPH1) catalyzes serotonin synthesis in peripheral tissues. Selective TPH1 inhibitors may be useful for treating disorders related to serotonin dysregulation. Results & methodology: Screening using a thermal shift assay for TPH1 binders yielded Compound 1 (2-(4-methylphenyl)-1,2-benzisothiazol-3(2 H)-one), which showed...

The metabolic network of sphingolipids plays important roles in cancer biology. Prominent sphingolipids include ceramides and sphingosine-1-phosphate that regulate multiple aspects of growth, apoptosis, and cellular signaling. Although a significant number of enzymatic regulators of the sphingolipid pathway have been described in detail, many remai...

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...

The metabolic network of sphingolipids plays important roles in cancer biology. Prominent sphingolipids include ceramides and sphingosine-1-phosphate that regulate multiple aspects of growth, apoptosis and cellular signaling. Although many significant enzymatic regulators of the sphingolipid pathway have been described in detail, the list is curren...

Hassallidins are cyclic glycolipopeptides produced by cyanobacteria and other prokaryotes. The hassallidin structure consists of a peptide ring of eight amino acids where a fatty acid chain, additional amino acids, and sugar moieties are attached. Hassallidins show antifungal activity against several opportunistic human pathogenic fungi, but does n...

Purpose: To clinically and genetically characterise a second family with dominant ARL3-related retinitis pigmentosa due to a specific ARL3 missense variant, p.(Tyr90Cys). Methods: Clinical examination included optical coherence tomography, electroretinography, and ultra-wide field retinal imaging with autofluorescence. Retrospective data were co...

The ER resident chaperone molecule GRP78 has been shown to translocate to the cell surface where it associates with Cripto and signals cell growth, playing a still partially understood role in tumorigenesis. Consequently, a better understanding of GRP78 topology and structure at the surface of cancer cells represents an important step in the develo...

Fig. S1. Representative sensorgrams for the binding of l‐Phe to different molecular forms of hPAH as determined by SPR analyses. Fig. S2. SDS/PAGE analysis of the purified recombinant hPAH proteins. Table S1. Oligonucleotides used for site‐directed mutagenesis.

Mammalian phenylalanine hydroxylase (PAH) is a key enzyme in l-phenylalanine (l-Phe) metabolism and is active as a homotetramer. Biochemical and biophysical work has demonstrated that it cycles between two states with a variably low and a high activity, and that the substrate l-Phe is the key player in this transition. X-ray structures of the catal...

Poster

The aromatic amino acid hydroxylase (AAAH) enzyme family includes phenylalanine hydroxylase (PAH), tyrosine hydroxylase (TH) and the tryptophan hydroxylases (TPH1 and TPH2). All four members of the AAAH family require iron, dioxygen and the cofactor (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4) to hydroxylate their respective substrates. The AAA...

In this manuscript we expand significantly on our earlier communication by investigating the bilayer self-assembly of eight different types of phospholipids in unbiased molecular dynamics (MD) simulations using the three major all-atom lipid force fields currently in use. Irrespective of the underlying force field, the lipids are shown to spontaneo...

Variants in the gene encoding the enzyme glutamic acid decarboxylase like 1 (GADL1) have been associated with response to lithium therapy. Both GADL1 and the related enzyme cysteine sulfinic acid decarboxylase (CSAD) have been proposed to be involved in the pyridoxal-5'-phosphate (PLP)-dependent biosynthesis of taurine. In the present study, we com...

Pharmacological chaperones are small compounds that correct the folding of mutant proteins, and represent a promising therapeutic strategy for misfolding diseases. We have performed a screening of 10 000 compounds searching for pharmacological chaperones of tyrosine hydroxylase (TH), the tetrahydrobiopterin (BH4)-dependent enzyme that catalyzes the...

This communication reports the first example of spontaneous lipid bilayer formation in unbiased all-atom molecular dynamics (MD) simulations. Using two different lipid force fields we show simulations started from random mixtures of lipids and water in which four different types of phospholipids self-assemble into organized bilayers in under 1 micr...

The nonheme iron and tetrahydrobiopterin dependent aromatic amino acid hydroxylases (AAAHs) comprise a family of enzymes that catalyse the hydroxylation of l ‐Phe, l ‐Tyr and l ‐Trp. These reactions are of central physiological importance. Consequently, dysfunction of the AAAHs is associated with serious disorders, that is, the genetic metabolic di...

Analogs of the cyclic nucleotides cAMP and cGMP have been extensively used to mimic or modulate cellular events mediated by protein kinase A (PKA), Exchange protein directly activated by cAMP (Epac), or protein kinase G (PKG). We report here that some of the most commonly used cyclic nucleotide analogs inhibit transmembrane transport mediated by th...

The AMBER lipid force field has been updated to create Lipid14, allowing tensionless simulation of a number of lipid types with the AMBER MD package. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The Lennard-Jones and tor...

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),...

Inhibition of ClpB, the bacterial representative of the heat-shock protein 100 family that is associated with virulence of several pathogens, could be an effective strategy to develop new antimicrobial agents. Using a high-throughput screening method, we have identified several compounds that bind to different conformations of ClpB, and analyzed th...

Phenylalanine hydroxylase (PAH) is a non-heme iron and tetrahydrobiopterin-dependent enzyme that catalyzes the hydroxylation of L-phenylalanine to L-tyrosine using dioxygen as additional substrate. The cofactor tetrahy-drobiopterin accepts one of the oxygen atoms of dioxygen during catalysis and also seems to be involved in pre-reduction of the act...

Sorbitol dehydrogenase inhibitors have been found to prevent, or alleviate, various secondary complications of diabetes mellitus. In the present study, the effects of nucleosides and nucleotides on the rate of sorbitol oxidation catalyzed by the sheep liver enzyme were studied by steady-state kinetics at pH 7.4. Various such compounds, including AT...

Despite recent improvement in therapy, acute myeloid leukemia (AML) is still associated with high lethality. In the presented study, we analyzed the bioactive compound iodinin (1,6-dihydroxyphenazine 5,10-dioxide) from a marine actinomycetes bacterium for the ability to induce cell death in a range of cell types. Iodinin showed selective toxicity t...

Accurate simulation of complex lipid bilayers has long been a goal in condensed phase molecular dynamics (MD). Structure and function of membrane-bound proteins are highly dependent on the lipid bilayer environment and are challenging to study through experimental methods. Within Amber, there has been limited focus on lipid simulations, although so...

Glucokinase (GK) is the central player in glucose-stimulated insulin release from pancreatic β-cells, and catalytic activation by α-D-glucose binding has a key regulatory function. Whereas the mechanism of this activation is well understood, on the basis of crystal structures of human GK, there are no similar structural data on ATP binding to the l...

Substrate hydroxylation by an FeIV=O cluster model of the active center in aromatic amino acid hydroxylases (AAHs) has been investigated by means of DFT calculations. Whereas benzene was used as a model for the aromatic amino acid substrate, the water-free FeIV=O cluster model has been used in previous studies of enzyme activation and formation of...

Fig. S1. Far-UV CD spectra of WT and T228M hGK. Fig. S2. The atom-positional backbone rmsd ofthe MD trajectory structures during the 2-ns MD simulations,relative to the starting structures, and calculated B-factorvalues based on fluctuations of Cα carbons during the 2-ns MD simulations of the four modelled structures. Fig. S3. Surface presentations...

The first part of the catalytic cycle of the pterin-dependent, dioxygen-using nonheme-iron aromatic amino acid hydroxylases, leading to the Fe(IV)=O hydroxylating intermediate, has been investigated by means of density functional theory. The starting structure in the present investigation is the water-free Fe-O(2) complex cluster model that represe...

Residual fluctuations of the closed unbound and ATP bound simulations for the intermediate and apical domains. Black bars show the RMSF values obtained from the ATP bound simulations, while red dots represent the unbound simulations. Binding site residues are depicted green, and the residues having the most significant changes are marked with label...

Difference contact maps between t, r, and r″ conformers. Difference in side chain contacts are mapped for the X-ray structures (A-E), and MD structures (F). Two residues are assumed to be in contact if the minimal distance between them is . Only contacts existing in at least half of the structures are considered. Green triangles represent contacts...

Statistics of projections of the MD conformers onto the first principal component. Each bar represents the projections (mean, median, or the last frame) of the simulations (only the 50–100 ns interval) onto the first principal component. The 6 apo and 6 holo simulations are depicted with grey and black bars, respectively. The full projections are p...

Overlap map of the X-ray and MD PCs. Squared overlap between pairs of eigenvectors obtained from X-ray and MD PCA are shown. Dark grey corresponds to values close to 1 (high similarity) while white depict overlap close to 0 (orthogonal). Root mean squared inner product (RMSIP) is provided according to ref. [78]. (EPS)

Time-dependent conformer plot of the 300 ns ATP-bound simulation. Projection of X-ray (contoured grey dots) and MD (blue) structures (along the simulation time) onto the two most significant principal planes defined by 287 GroEL experimentally obtained structures. The distribution of MD structures is depicted with density shaded blue points. Orange...

The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the...

GroEL is an ATP dependent molecular chaperone that promotes the folding of a large number of substrate proteins in E. coli. Large-scale conformational transitions occurring during the reaction cycle have been characterized from extensive crystallographic studies. However, the link between the observed conformations and the mechanisms involved in th...

Local anesthetics (LAs) are drugs that cause reversible loss of nociception during surgical procedures. Articaine is a commonly used LA in dentistry that has proven to be exceptionally effective in penetrating bone tissue and induce anesthesia on posterior teeth in maxilla and mandibula. In the present study, our aim was to gain a deeper understand...

This chapter presents the information on the function and structure of the amino acid hydroxylases (AAHs), the objectives is to offer information on the catalytic mechanism operating in these non-heme iron-dependent enzymes. In particular, the chapter focuses on mechanistically relevant information that has emerged from molecular-level computationa...

Phenylalanine hydroxylase (PAH) catalyzes the hydroxylation of L-Phe to L-Tyr. Dysfunctional PAH results in phenylketonuria and mammalian PAH is therefore highly regulated and displays positive cooperativity for L-Phe (Hill coefficient (h)=2). L-Phe does not bind to the regulatory ACT domain in full-length tetrameric human PAH and cooperativity is...

Phenylalanine hydroxylase (PAH) catalyzes the hydroxylation of L-phenylalanine to L-tyrosine and is dependent on the contribution of electrons from the reduced cofactor tetrahydrobiopterin (BH4). Whereas three ligating water molecules are bound to the central iron atom in the existing crystal structures of binary complexes of the catalytic domain o...

Phenylalanine hydroxylase (PAH) catalyzes the para-hydroxylation of L-Phe to L-Tyr, which in mammals is the first step in the catabolic degradation of L-Phe. Defects in PAH, notably due to mutations in the PAH gene, result in high concentrations of L-Phe in plasma, causing phenylketonuria (PKU) in humans. In order to maintain L-Phe homeostasis, PAH...

The understanding of biomolecular interactions ultimately depends on knowledge about the structural and dynamic details of the interacting system. Rational structure-based drug design implements computational methodology in this rationale. Together with increasing throughput of structural biology, molecular modeling has progressively contributed to...

Misfolding diseases are a group of harmful disorders in which the main molecular mechanism for loss of gene function is either an accelerated degradation of the protein or its aggregation inside or outside the cell. Phenylketonuria (PKU) is a disease caused by deleterious mutations in phenylalanine hydroxylase (PAH) and constitutes a paradigm for m...

We here present a method for estimating the accessible volume surrounding each atom of a ligand when bound to a receptor. The accessible volumes are calculated as the volume of a sphere with fixed radius, centered on each ligand atom, not simultaneously occupied by the volume of the receptor. The method is capable of describing the packing of the l...

Hydroxylation of the aromatic amino acids phenylalanine, tyrosine and tryptophan is carried out by a family of non-heme iron and tetrahydrobiopterin (BH4) dependent enzymes, i.e. the aromatic amino acid hydroxylases (AAHs). The reactions catalyzed by these enzymes are important for biomedicine and their mutant forms in humans are associated with ph...

Pterin-4a-carbinolamine dehydratase (PCD) is an essential component of the phenylalanine hydroxylase (PAH) system, catalyzing the regeneration of the essential cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin [6(R)BH4]. Mutations in PCD or its deactivation by hydrogen peroxide result in the generation of 7(R,S)BH4, which is a potent inhibitor of...

The cAMP-dependent protein kinase (PKA I and II) and the cAMP-stimulated GDP exchange factors (Epac1 and -2) are major cAMP effectors. The cAMP affinity of the PKA holoenzyme has not been determined previously. We found that cAMP bound to PKA I with a K(d) value (2.9 microM) similar to that of Epac1. In contrast, the free regulatory subunit of PKA...

The three aromatic amino acid hydroxylases (phenylalanine, tyrosine, and tryptophan hydroxylase) and nitric oxide synthase (NOS) all utilize (6R)-l-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)) as cofactor. The pterin binding site in the three hydroxylases is well conserved and different from the binding site in NOS. The structures of phenylalanine h...

Phenylalanine hydroxylase (PAH) is the key enzyme in the catabolism of L-Phe. The natural cofactor of PAH, 6R-tetrahydrobiopterin (BH4), negatively regulates the enzyme activity in addition to being an essential cosubstrate for catalysis. The analogue 6-methyltetrahydropterin (6M-PH4) is effective in catalysis but does not regulate PAH. Here, the t...

Phosphorylation of phenylalanine hydroxylase (PAH) at Ser16 by cAMP-dependent protein kinase increases the basal activity of the enzyme and its resistance to tryptic proteolysis. The modeled structures of the full-length phosphorylated and unphosphorylated enzyme were subjected to molecular dynamics simulations, and we analyzed the energy of charge...

Phenylalanine hydroxylase (PAH) is a tetrahydrobiopterin-dependent enzyme that catalyzes the hydroxylation of L-phenylalanine (L-Phe) to L-tyrosine using dioxygen as an additional substrate. The requirement of PAH for a cofactor is absolute, but several cofactor analogs are able to substitute the natural cofactor in catalysis. However, it is only t...

Phenylalanine hydroxylase (PAH) is a multidomain tetrameric enzyme that displays positive cooperative substrate binding. This cooperative response is believed to be of physiological significance as a mechanism that controls L-Phe homeostasis in blood. The substrate induces an activating conformational change in the enzyme affecting the secondary, t...

Phosphorylation of phenylalanine hydroxylase (PAH) at Ser(16) by cyclic AMP-dependent protein kinase is a post-translational modification that increases its basal activity and facilitates its activation by the substrate l-Phe. So far there is no structural information on the flexible N-terminal tail (residues 1-18), including the phosphorylation si...

Phosphorylation of phenylalanine hydroxylase (PAH) at Ser16 by cyclic AMP-dependent protein kinase is a post-translational modification that increases its basal activity and facilitates its activation by the substrate l-Phe. So far there is no structural information on the flexible N-terminal tail (residues 1–18), including the phosphorylation site...

Phenylalanine hydroxylase (PAH), tyrosine hydroxylase (TH), tryptophan hydroxylase (TPH) and nitric oxide synthase (NOS) are tetrahydrobiopterin (BH4)-dependent enzymes that catalyze the hydroxylation of the respective aromatic amino acids (PAH, TH and TPH) and the synthesis of NO from arginine (NOS), using dioxygen as additional substrate. While t...

Tryptophan hydroxylase (TPH) is a tetrahydrobiopterin (BH4)- and iron-dependent enzyme that hydroxylates L-Trp to 5-hydroxy-L-Trp using molecular oxygen. This is the rate limiting step in the synthesis of serotonin. Due to the scarcity of the enzyme in animal tissues and its instability in vitro, TPH is the least characterized of the three aromatic...

Tryptophan hydroxylase (TPH) carries out the 5-hydroxylation of l-Trp, which is the rate-limiting step in the synthesis of serotonin. We have prepared and characterized a stable N-terminally truncated form of human TPH that includes the catalytic domain (Δ90TPH). We have also determined the conformation and distances to the catalytic non-heme iron...

Tetrahydropterins are obligatory cofactors for tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis. A series of synthetic analogues of 6(R)-l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) with different substituents in positions C2, N3, C4, N5, C6, C7, and N8 on the ring were used as active site probes for recombinant huma...

Phenylalanine hydroxylase (PAH) is a tetrahydrobiopterin and non-heme iron-dependent enzyme that hydroxylates L-Phe to l-Tyr using molecular oxygen as additional substrate. A dysfunction of this enzyme leads to phenylketonuria (PKU). The conformation and distances to the catalytic iron of both L-Phe and the cofactor analogue L-erythro-7,8-dihydrobi...

In vitro activity of 4 commonly used and 5 new antibiotics was examined against 177 strains of Haemophilus influenzae. All strains were collected from various sites in patients with clinical infections. The study confirms that several newer antibiotics are useful alternatives to older drugs, as measured by in vitro activity. Ciprofloxacin and oflox...