Acta Crystallographica. Section F : Structural Biology and Crystallization Communications, Jun 27, 2009
The tetramerization domain (T1 domain) derived from the voltage-dependent potassium channel Kv1.3... more The tetramerization domain (T1 domain) derived from the voltage-dependent potassium channel Kv1.3 of Homo sapiens was recombinantly expressed in Escherichia coli and purified. The crystals were first grown in an NMR tube in 150 mM potassium phosphate pH 6.5 in the absence of additional precipitants. The crystals showed I4 symmetry characteristic of the naturally occurring tetrameric assembly of the single subunits. A complete native data set was collected to 1.2 A resolution at 100 K using synchrotron radiation.
Whereas the self-assembly of pentaphosphaferrocenes [CpRFe(η5-P5)] (CpR = Cp*, Cp×, and CpBn) wit... more Whereas the self-assembly of pentaphosphaferrocenes [CpRFe(η5-P5)] (CpR = Cp*, Cp×, and CpBn) with Cu and Ag salts has been well-studied in the past, the coordination chemistry toward Au complexes has been left untouched so far. Herein, the results of the self-assembly processes of [CpRFe(η5-P5)] with Au salts of different anions (GaCl4-, SbF6-, and Al(OC(CF3)3)4 (TEF-)) are reported. Next to a variety of molecular coordination products, the first coordination polymers based on polyphosphorus ligand complexes and Au salts are also obtained. Thereby, a 2D coordination polymer comprising metal vacancies is isolated. In all products, the Au centers are coordinated in a linear or a trigonal planar environment. In solution, highly dynamic processes are observed. Variable-temperature NMR spectroscopy, solid-state NMR spectroscopy, and X-ray powder diffraction were applied to gain further insight into selected coordination compounds.
Abstract In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe (1), Ru (2)) wit... more Abstract In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe (1), Ru (2)) with I2 resulted in the selective formation of [Cp*MP6I6]+ salts (3, 4). The products comprise unprecedented all‐cis tripodal triphosphino‐cyclotriphosphine ligands. The iodination of [Cp*Fe(η5‐As5)] (6) gave, in addition to [Fe(CH3CN)6]2+ salts of the rare [As6I8]2− (in 7) and [As4I14]2− (in 8) anions, the first di‐cationic Fe‐As triple decker complex [(Cp*Fe)2(μ,η5:5‐As5)][As6I8] (9). In contrast, the iodination of [Cp*Ru(η5‐As5)] (10) did not result in the full cleavage of the M−As bonds. Instead, a number of dinuclear complexes were obtained: [(Cp*Ru)2(μ,η5:5‐As5)][As6I8]0.5 (11) represents the first Ru‐As5 triple decker complex, thus completing the series of monocationic complexes [(CpRM)2(μ,η5:5‐E5)]+ (M=Fe, Ru; E=P, As). [(Cp*Ru)2As8I6] (12) crystallizes as a racemic mixture of both enantiomers, while [(Cp*Ru)2As4I4] (13) crystallizes as a symmetric and an asymmetric isomer and features a unique tetramer of {AsI} arsinidene units as a middle deck.
One-pot self-assembly reactions of the polyphosphorus complex [Cp*Fe(h 5-P 5)] (A), ac oinage met... more One-pot self-assembly reactions of the polyphosphorus complex [Cp*Fe(h 5-P 5)] (A), ac oinage metal salt AgSbF 6 ,a nd flexible aliphatic dinitriles NC(CH 2) x CN (x = 1-10) yield 1D,2 D, and 3D coordination polymers.T he sevenmembered backbone of the dinitrile was experimentally found as the borderline for the self-assembly system furnishing products of different kinds.A tx < 7, various rather simple polymers are exclusively formed possessing either 0D or 1D Ag/A structural motifs connected by dinitrile spacers,while at x ! 7, the self-assembly switches to unprecedented extraordinary 3D networks of nano-sized host-guest assemblies (SbF 6)@[(A) 9 Ag 11 ] 11+ (x = 7) or (A)@[(A) 12 Ag 12 ] 12+ (x = 8-10) linked by dinitriles.T he polycationic nodes represent the first superspheres based on A and silver and are host-guest able.A ll products are characterized by NMR spectroscopy, mass spectrometry,a nd single-crystal X-rayd iffraction. The assemblies [(A) 12 Ag 12 ] 12+ were visualized by transmission electron microscopy.
The 72-kDa immediate early 1 (IE1) protein encoded by human cytomegalovirus (hCMV) is a nuclearly... more The 72-kDa immediate early 1 (IE1) protein encoded by human cytomegalovirus (hCMV) is a nuclearly localized promiscuous regulator of viral and cellular transcription. IE1 has long been known to associate with host mitotic chromatin, yet the mechanisms underlying this interaction have not been specified. In this study, we identify the cellular chromosome receptor for IE1. We demonstrate that the viral protein targets human nucleosomes by directly binding to core histones in a nucleic acid-independent manner. IE1 exhibits two separable histone-interacting regions with differential binding specificities for H2A-H2B and H3-H4. The H2A-H2B binding region was mapped to an evolutionarily conserved 10-amino-acid motif within the chromatin-tethering domain (CTD) of IE1. Results from experimental approaches combined with molecular modeling indicate that the IE1 CTD adopts a β-hairpin structure, docking with the acidic pocket formed by H2A-H2B on the nucleosome surface. IE1 binds to the acidic...
Prokaryotic cold shock proteins (CSPs) are considered to play an important role in the transcript... more Prokaryotic cold shock proteins (CSPs) are considered to play an important role in the transcriptional and translational regulation of gene expression, possibly by acting as transcription anti-terminators and “RNA chaperones”. They bind with high affinity to single-stranded nucleic acids. Here we report the binding epitope of TmCsp from Thermotoga maritima for both single-stranded DNA and RNA, using heteronuclear 2D NMR spectroscopy. At “physiological” growth temperatures of TmCsp (≥ 343 K), all oligonucleotides studied have dissociation constants between 1.6 ((dT)7) and 25.2 ((dA)7) μM as determined by tryptophan fluorescence quenching. Reduction of the temperature to 303 K leads to a pronounced increase of affinity for thymidylate (dT)7 and uridylate (rU)7 heptamers with dissociation constants of 4.0 and 10.8 nM, respectively, whereas the weak binding of TmCsp to cytidylate, adenylate, and guanylate heptamers (dC)7, (dA)7, and (dT)7 is almost unaffected by temperature. The change ...
In the original publication, Figures 3 and 6 were displayed incorrectly due to a mistake made by ... more In the original publication, Figures 3 and 6 were displayed incorrectly due to a mistake made by the publisher. The correct version of Figs. 3 and 6 are given below.
Prostate cancer (PCa) diagnosis with current biomarkers is difficult and often results in unneces... more Prostate cancer (PCa) diagnosis with current biomarkers is difficult and often results in unnecessary invasive procedures as well as over-diagnosis and over-treatment, highlighting the need for novel biomarkers. The aim of this review is to provide a summary of available metabolomics PCa biomarkers, particularly for clinically significant disease. A systematic search was conducted on PubMed for publications from July 2008 to July 2018 in accordance with PRISMA guidelines to report biomarkers with respect to their application in PCa diagnosis, progression, aggressiveness, recurrence, and treatment response. The vast majority of studies report biomarkers with the ability to distinguish malignant from benign prostate tissue with a few studies investigating biomarkers associated with disease progression, treatment response or tumour recurrence. In general, these studies report high dimensional datasets and the number of analysed metabolites often significantly exceeded the number of ava...
The storage of metastable compounds and modifications of elements are of great interest for synth... more The storage of metastable compounds and modifications of elements are of great interest for synthesis and other, e.g., semiconductor, applications. Whereas white phosphorus is a metastable modification that can be stored under certain conditions, storage of the extremely (light-and air-)sensitive form of arsenic, yellow arsenic, is a challenge rarely tackled so far. Herein, we report on the facile storage and release of these tetrahedral E 4 molecules (E = P, As) using activated carbon as a porous storage material. These loaded materials are air-and light-stable and have been comprehensively characterized by solid-state 31 P{ 1 H} MAS NMR spectroscopy, powder X-ray diffraction analysis, nitrogen adsorption measurements, and thermogravimetric analysis. Additionally, we show that these materials can be used as a suitable E 4 source for releasing intact white phosphorus or yellow arsenic, enabling subsequent reactions in solution. Because the uptake and release of E 4 are reversible, these materials are excellent carriers of these highly reactive modifications.
Berichte der Bunsengesellschaft für physikalische Chemie
The microwave conductivity in dependence of temperature was measured on pure aod iodine doped cry... more The microwave conductivity in dependence of temperature was measured on pure aod iodine doped crystals or a..(BEDT.1TFht) along the stack direction [100] and perpendicular to it [010]. The: uposure times 10 iodine were varied in many step!! between 2 mio and 360 min. The coouctless microwave technique enables to keep tbe same crystal in each case throughout all measurements.-The results show that the microwave conductivity vs. lemperalUre is not influenced distinctly by iodine doping. Only at the onset or the plateau range immediately below the metal•insolator transition at 135 K a small enhancement of the conductivity is round for exposure times larger than 60 min.-In 00 case a transition to a lIupercooductiog state is observed. Thererore recently reported superconductivity may be due to surface effects.
pressure. The valine and leucine methyl groups in the model peptides were assigned using stereosp... more pressure. The valine and leucine methyl groups in the model peptides were assigned using stereospecifically 13 C enriched amino acids with the pro-R carbons downfield shifted relative to the proS carbons.
High pressure NMR spectroscopy is a powerful method for identifying rare conformational states of... more High pressure NMR spectroscopy is a powerful method for identifying rare conformational states of proteins from the pressure response of their chemical shifts. Many proteins have bound adenine nucleotides at their active centers, in most cases in a complex with Mg(2+)-ions. The (31)P NMR signals of phosphate groups of the nucleotides can be used as probes for conformational transitions in the proteins themselves. For distinguishing protein specific pressure effects from trivial pressure responses not due to the protein interaction, data of the pressure response of the free nucleotides must be available. Therefore, the pressure response of (31)P chemical shifts of the adenine nucleotides AMP, ADP, and ATP and their Mg(2+)-complexes has been determined at pH values several units distant from the respective pK-values. It is clearly non-linear for most of the resonances. A negative first order pressure coefficient B1 was determined for all (31)P resonances except Mg(2+)·AMP indicating an upfield shift of the resonances with pressure. The smallest and largest negative values are obtained for the α-phosphate group of ADP and β-phosphate group of Mg(2+)·ATP with -0.32 and -4.59ppm/GPa, respectively. With exception of the α-phosphate group of Mg(2+)·AMP the second order pressure coefficients are positive leading to a saturation like behaviour. The pressure response of the adenine nucleotides is similar but not identical to that observed earlier for guanine nucleotides. The obtained data show that the chemical shift pressure response of the different phosphate groups is rather different dependent on the position of phosphate group in the nucleotide and the nucleotide used.
The (31)P NMR pressure response of guanine nucleotides bound to proteins has been studied in the ... more The (31)P NMR pressure response of guanine nucleotides bound to proteins has been studied in the past for characterizing the pressure perturbation of conformational equilibria. The pressure response of the (31)P NMR chemical shifts of the phosphate groups of GMP, GDP, and GTP as well as the commonly used GTP analogs GppNHp, GppCH2p and GTPγS was measured in the absence and presence of Mg(2+)-ions within a pressure range up to 200 MPa. The pressure dependence of chemical shifts is clearly non-linear. For all nucleotides a negative first order pressure coefficient B 1 was determined indicating an upfield shift of the resonances with pressure. With exception of the α-phosphate group of Mg(2+)·GMP and Mg(2+)·GppNHp the second order pressure coefficients are positive. To describe the data of Mg(2+)·GppCH2p and GTPγS a Taylor expansion of 3rd order is required. For distinguishing pH effects from pressure effects a complete pH titration set is presented for GMP, as well as GDP and GTP in a...
Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with t... more Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with three unique protein families, the pleuralins, frustulins, and silaffins. The NMR structure of the PSCD4 domain of pleuralin-1 from Cylindrotheca fusiformis contains only three short helical elements and is stabilized by five unique disulfide bridges. PSCD4 contains two binding sites for Ca(2+) ions with millimolar affinity. NMR-based interaction studies show an interaction of the domain with native silaffin-1A as well as with α-frustulins. The interaction sites of the two proteins mapped on the PSCD4 structure are contiguous and show only a small overlap. A plausible functional role of pleuralin could be to bind simultaneously silaffin-1A located inside the cell wall and α-frustulin coating the cell wall, thus connecting the interfaces between hypotheca and epitheca at the girdle bands. Restrained molecular dynamics calculations suggest a bead-chain-like structure of the central part of ...
Acta Crystallographica. Section F : Structural Biology and Crystallization Communications, Jun 27, 2009
The tetramerization domain (T1 domain) derived from the voltage-dependent potassium channel Kv1.3... more The tetramerization domain (T1 domain) derived from the voltage-dependent potassium channel Kv1.3 of Homo sapiens was recombinantly expressed in Escherichia coli and purified. The crystals were first grown in an NMR tube in 150 mM potassium phosphate pH 6.5 in the absence of additional precipitants. The crystals showed I4 symmetry characteristic of the naturally occurring tetrameric assembly of the single subunits. A complete native data set was collected to 1.2 A resolution at 100 K using synchrotron radiation.
Whereas the self-assembly of pentaphosphaferrocenes [CpRFe(η5-P5)] (CpR = Cp*, Cp×, and CpBn) wit... more Whereas the self-assembly of pentaphosphaferrocenes [CpRFe(η5-P5)] (CpR = Cp*, Cp×, and CpBn) with Cu and Ag salts has been well-studied in the past, the coordination chemistry toward Au complexes has been left untouched so far. Herein, the results of the self-assembly processes of [CpRFe(η5-P5)] with Au salts of different anions (GaCl4-, SbF6-, and Al(OC(CF3)3)4 (TEF-)) are reported. Next to a variety of molecular coordination products, the first coordination polymers based on polyphosphorus ligand complexes and Au salts are also obtained. Thereby, a 2D coordination polymer comprising metal vacancies is isolated. In all products, the Au centers are coordinated in a linear or a trigonal planar environment. In solution, highly dynamic processes are observed. Variable-temperature NMR spectroscopy, solid-state NMR spectroscopy, and X-ray powder diffraction were applied to gain further insight into selected coordination compounds.
Abstract In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe (1), Ru (2)) wit... more Abstract In a high‐yield one‐pot synthesis, the reactions of [Cp*M(η5‐P5)] (M=Fe (1), Ru (2)) with I2 resulted in the selective formation of [Cp*MP6I6]+ salts (3, 4). The products comprise unprecedented all‐cis tripodal triphosphino‐cyclotriphosphine ligands. The iodination of [Cp*Fe(η5‐As5)] (6) gave, in addition to [Fe(CH3CN)6]2+ salts of the rare [As6I8]2− (in 7) and [As4I14]2− (in 8) anions, the first di‐cationic Fe‐As triple decker complex [(Cp*Fe)2(μ,η5:5‐As5)][As6I8] (9). In contrast, the iodination of [Cp*Ru(η5‐As5)] (10) did not result in the full cleavage of the M−As bonds. Instead, a number of dinuclear complexes were obtained: [(Cp*Ru)2(μ,η5:5‐As5)][As6I8]0.5 (11) represents the first Ru‐As5 triple decker complex, thus completing the series of monocationic complexes [(CpRM)2(μ,η5:5‐E5)]+ (M=Fe, Ru; E=P, As). [(Cp*Ru)2As8I6] (12) crystallizes as a racemic mixture of both enantiomers, while [(Cp*Ru)2As4I4] (13) crystallizes as a symmetric and an asymmetric isomer and features a unique tetramer of {AsI} arsinidene units as a middle deck.
One-pot self-assembly reactions of the polyphosphorus complex [Cp*Fe(h 5-P 5)] (A), ac oinage met... more One-pot self-assembly reactions of the polyphosphorus complex [Cp*Fe(h 5-P 5)] (A), ac oinage metal salt AgSbF 6 ,a nd flexible aliphatic dinitriles NC(CH 2) x CN (x = 1-10) yield 1D,2 D, and 3D coordination polymers.T he sevenmembered backbone of the dinitrile was experimentally found as the borderline for the self-assembly system furnishing products of different kinds.A tx < 7, various rather simple polymers are exclusively formed possessing either 0D or 1D Ag/A structural motifs connected by dinitrile spacers,while at x ! 7, the self-assembly switches to unprecedented extraordinary 3D networks of nano-sized host-guest assemblies (SbF 6)@[(A) 9 Ag 11 ] 11+ (x = 7) or (A)@[(A) 12 Ag 12 ] 12+ (x = 8-10) linked by dinitriles.T he polycationic nodes represent the first superspheres based on A and silver and are host-guest able.A ll products are characterized by NMR spectroscopy, mass spectrometry,a nd single-crystal X-rayd iffraction. The assemblies [(A) 12 Ag 12 ] 12+ were visualized by transmission electron microscopy.
The 72-kDa immediate early 1 (IE1) protein encoded by human cytomegalovirus (hCMV) is a nuclearly... more The 72-kDa immediate early 1 (IE1) protein encoded by human cytomegalovirus (hCMV) is a nuclearly localized promiscuous regulator of viral and cellular transcription. IE1 has long been known to associate with host mitotic chromatin, yet the mechanisms underlying this interaction have not been specified. In this study, we identify the cellular chromosome receptor for IE1. We demonstrate that the viral protein targets human nucleosomes by directly binding to core histones in a nucleic acid-independent manner. IE1 exhibits two separable histone-interacting regions with differential binding specificities for H2A-H2B and H3-H4. The H2A-H2B binding region was mapped to an evolutionarily conserved 10-amino-acid motif within the chromatin-tethering domain (CTD) of IE1. Results from experimental approaches combined with molecular modeling indicate that the IE1 CTD adopts a β-hairpin structure, docking with the acidic pocket formed by H2A-H2B on the nucleosome surface. IE1 binds to the acidic...
Prokaryotic cold shock proteins (CSPs) are considered to play an important role in the transcript... more Prokaryotic cold shock proteins (CSPs) are considered to play an important role in the transcriptional and translational regulation of gene expression, possibly by acting as transcription anti-terminators and “RNA chaperones”. They bind with high affinity to single-stranded nucleic acids. Here we report the binding epitope of TmCsp from Thermotoga maritima for both single-stranded DNA and RNA, using heteronuclear 2D NMR spectroscopy. At “physiological” growth temperatures of TmCsp (≥ 343 K), all oligonucleotides studied have dissociation constants between 1.6 ((dT)7) and 25.2 ((dA)7) μM as determined by tryptophan fluorescence quenching. Reduction of the temperature to 303 K leads to a pronounced increase of affinity for thymidylate (dT)7 and uridylate (rU)7 heptamers with dissociation constants of 4.0 and 10.8 nM, respectively, whereas the weak binding of TmCsp to cytidylate, adenylate, and guanylate heptamers (dC)7, (dA)7, and (dT)7 is almost unaffected by temperature. The change ...
In the original publication, Figures 3 and 6 were displayed incorrectly due to a mistake made by ... more In the original publication, Figures 3 and 6 were displayed incorrectly due to a mistake made by the publisher. The correct version of Figs. 3 and 6 are given below.
Prostate cancer (PCa) diagnosis with current biomarkers is difficult and often results in unneces... more Prostate cancer (PCa) diagnosis with current biomarkers is difficult and often results in unnecessary invasive procedures as well as over-diagnosis and over-treatment, highlighting the need for novel biomarkers. The aim of this review is to provide a summary of available metabolomics PCa biomarkers, particularly for clinically significant disease. A systematic search was conducted on PubMed for publications from July 2008 to July 2018 in accordance with PRISMA guidelines to report biomarkers with respect to their application in PCa diagnosis, progression, aggressiveness, recurrence, and treatment response. The vast majority of studies report biomarkers with the ability to distinguish malignant from benign prostate tissue with a few studies investigating biomarkers associated with disease progression, treatment response or tumour recurrence. In general, these studies report high dimensional datasets and the number of analysed metabolites often significantly exceeded the number of ava...
The storage of metastable compounds and modifications of elements are of great interest for synth... more The storage of metastable compounds and modifications of elements are of great interest for synthesis and other, e.g., semiconductor, applications. Whereas white phosphorus is a metastable modification that can be stored under certain conditions, storage of the extremely (light-and air-)sensitive form of arsenic, yellow arsenic, is a challenge rarely tackled so far. Herein, we report on the facile storage and release of these tetrahedral E 4 molecules (E = P, As) using activated carbon as a porous storage material. These loaded materials are air-and light-stable and have been comprehensively characterized by solid-state 31 P{ 1 H} MAS NMR spectroscopy, powder X-ray diffraction analysis, nitrogen adsorption measurements, and thermogravimetric analysis. Additionally, we show that these materials can be used as a suitable E 4 source for releasing intact white phosphorus or yellow arsenic, enabling subsequent reactions in solution. Because the uptake and release of E 4 are reversible, these materials are excellent carriers of these highly reactive modifications.
Berichte der Bunsengesellschaft für physikalische Chemie
The microwave conductivity in dependence of temperature was measured on pure aod iodine doped cry... more The microwave conductivity in dependence of temperature was measured on pure aod iodine doped crystals or a..(BEDT.1TFht) along the stack direction [100] and perpendicular to it [010]. The: uposure times 10 iodine were varied in many step!! between 2 mio and 360 min. The coouctless microwave technique enables to keep tbe same crystal in each case throughout all measurements.-The results show that the microwave conductivity vs. lemperalUre is not influenced distinctly by iodine doping. Only at the onset or the plateau range immediately below the metal•insolator transition at 135 K a small enhancement of the conductivity is round for exposure times larger than 60 min.-In 00 case a transition to a lIupercooductiog state is observed. Thererore recently reported superconductivity may be due to surface effects.
pressure. The valine and leucine methyl groups in the model peptides were assigned using stereosp... more pressure. The valine and leucine methyl groups in the model peptides were assigned using stereospecifically 13 C enriched amino acids with the pro-R carbons downfield shifted relative to the proS carbons.
High pressure NMR spectroscopy is a powerful method for identifying rare conformational states of... more High pressure NMR spectroscopy is a powerful method for identifying rare conformational states of proteins from the pressure response of their chemical shifts. Many proteins have bound adenine nucleotides at their active centers, in most cases in a complex with Mg(2+)-ions. The (31)P NMR signals of phosphate groups of the nucleotides can be used as probes for conformational transitions in the proteins themselves. For distinguishing protein specific pressure effects from trivial pressure responses not due to the protein interaction, data of the pressure response of the free nucleotides must be available. Therefore, the pressure response of (31)P chemical shifts of the adenine nucleotides AMP, ADP, and ATP and their Mg(2+)-complexes has been determined at pH values several units distant from the respective pK-values. It is clearly non-linear for most of the resonances. A negative first order pressure coefficient B1 was determined for all (31)P resonances except Mg(2+)·AMP indicating an upfield shift of the resonances with pressure. The smallest and largest negative values are obtained for the α-phosphate group of ADP and β-phosphate group of Mg(2+)·ATP with -0.32 and -4.59ppm/GPa, respectively. With exception of the α-phosphate group of Mg(2+)·AMP the second order pressure coefficients are positive leading to a saturation like behaviour. The pressure response of the adenine nucleotides is similar but not identical to that observed earlier for guanine nucleotides. The obtained data show that the chemical shift pressure response of the different phosphate groups is rather different dependent on the position of phosphate group in the nucleotide and the nucleotide used.
The (31)P NMR pressure response of guanine nucleotides bound to proteins has been studied in the ... more The (31)P NMR pressure response of guanine nucleotides bound to proteins has been studied in the past for characterizing the pressure perturbation of conformational equilibria. The pressure response of the (31)P NMR chemical shifts of the phosphate groups of GMP, GDP, and GTP as well as the commonly used GTP analogs GppNHp, GppCH2p and GTPγS was measured in the absence and presence of Mg(2+)-ions within a pressure range up to 200 MPa. The pressure dependence of chemical shifts is clearly non-linear. For all nucleotides a negative first order pressure coefficient B 1 was determined indicating an upfield shift of the resonances with pressure. With exception of the α-phosphate group of Mg(2+)·GMP and Mg(2+)·GppNHp the second order pressure coefficients are positive. To describe the data of Mg(2+)·GppCH2p and GTPγS a Taylor expansion of 3rd order is required. For distinguishing pH effects from pressure effects a complete pH titration set is presented for GMP, as well as GDP and GTP in a...
Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with t... more Diatoms are eukaryotic unicellular algae characterized by silica cell walls and associated with three unique protein families, the pleuralins, frustulins, and silaffins. The NMR structure of the PSCD4 domain of pleuralin-1 from Cylindrotheca fusiformis contains only three short helical elements and is stabilized by five unique disulfide bridges. PSCD4 contains two binding sites for Ca(2+) ions with millimolar affinity. NMR-based interaction studies show an interaction of the domain with native silaffin-1A as well as with α-frustulins. The interaction sites of the two proteins mapped on the PSCD4 structure are contiguous and show only a small overlap. A plausible functional role of pleuralin could be to bind simultaneously silaffin-1A located inside the cell wall and α-frustulin coating the cell wall, thus connecting the interfaces between hypotheca and epitheca at the girdle bands. Restrained molecular dynamics calculations suggest a bead-chain-like structure of the central part of ...
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Papers by Werner Kremer