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Mayntz D, Raubenheimer D, Salomon M, Toft S, Simpson SJ. Nutrient-specific foraging in invertebrate predators. Science 2005; 307:111-3. [PMID: 15637278 DOI: 10.1126/science.1105493] [Citation(s) in RCA: 241] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Many herbivores and omnivores adjust their food selection behavior to regulate the intake of multiple nutrients. Carnivores, however, are generally assumed to optimize the rate of prey capture rather than select prey according to nutrient composition. We showed experimentally that invertebrate predators can forage selectively for protein and lipids to redress specific nutritional imbalances. This selection can take place at different stages of prey handling: The predator may select among foods of different nutritional composition, eat more of a prey if it is rich in nutrients that the predator is deficient in, or extract specific nutrients from a single prey item.
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Lemos D, Salomon M, Gomes V, Phan VN, Buchholz F. Citrate synthase and pyruvate kinase activities during early life stages of the shrimp Farfantepenaeus paulensis (Crustacea, Decapoda, Penaeidae): effects of development and temperature. Comp Biochem Physiol B Biochem Mol Biol 2003; 135:707-19. [PMID: 12892763 DOI: 10.1016/s1096-4959(03)00166-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Energy metabolism in early life stages of the shrimp Farfantepenaeus paulensis subjected to temperature reduction (26 and 20 degrees C) was determined using the activities of citrate synthase (CS) and pyruvate kinase (PK). At both temperatures, weight-specific activity of CS decreased throughout the ontogenetic development from protozoea II (PZ II) to postlarva XII-XIV (PL XII-XIV). PK activity reached a pronounced peak in PL V-VI, followed by a further decrease in PL XII-XIV. Temperature reduction produced variation in oxygen consumption rates (QO(2)), ammonia-N excretion and in enzyme activities. Ammonia-N excretion was higher at 20 degrees C in mysis III (M III), PL V-VI and PL XII-XIV, resulting in substantially lower O:N ratios in these stages. QO(2) was increased in protozoea II (PZ II) and mysis I (M I) at 26 degrees C, while no difference in QO(2) was detected in the subsequent stages at either temperature. This fact coincided with higher CS and PK activities in M III, PL V-VI and PL XII-XIV at 20 degrees C compared with 26 degrees C. Regressions between individual enzyme activities and dry weight exhibited slope values of 0.85-0.92 for CS and 1.1-1.2 for PK and temperature reduction was reflected by higher slope values at 20 than at 26 degrees C for both enzymes. Weight-specific CS activity was positively correlated with QO(2) at 20 and 26 degrees C, and may thus be used as an indicator of aerobic metabolic rate throughout the early stages of F. paulensis. The variation in enzyme activities is discussed in relation to possible metabolic adaptations during specific ontogenetic events of the F. paulensis life cycle. Here, the catalytic efficiency of energy-metabolism enzymes was reflected in ontogenetic shifts in behaviour such as larval settlement and the adoption of a benthic existence in early postlarvae. In most cases, enhanced enzyme activities appeared to counteract negative effects of reduced temperature.
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Salomon M, Conway BE. Potentiostatic Determination of Electrolytic Hydrogen-Deuterium Separation Factors and the Reaction Mechanism at Mercury and Platinum. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100789a507] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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McIntyre JDE, Salomon M. Kinetic isotope effects in the hydrogen electrode reaction. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100853a026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cohen-Adad R, Lorimer JW, Phillips SL, Salomon M. A Consistent Approach to Tabulation of Evaluated Solubility Data: Application to the Binary Systems RbCl-H2O and UO2(NO3)2-H2O. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/ci00026a003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Helbig AJ, Salomon M, Bensch S, Seibold I. Male-biased gene flow across an avian hybrid zone: evidence from mitochondrial and microsatellite DNA. J Evol Biol 2001. [DOI: 10.1046/j.1420-9101.2001.00273.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Schleiff E, Tien R, Salomon M, Soll J. Lipid composition of outer leaflet of chloroplast outer envelope determines topology of OEP7. Mol Biol Cell 2001; 12:4090-102. [PMID: 11739803 PMCID: PMC60778 DOI: 10.1091/mbc.12.12.4090] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
OEP7, a 6.7-kDa outer envelope protein of spinach chloroplasts inserts into the outer envelope of the organelle independent of a classical cleavable targeting signal. The insertion of OEP7 was studied to describe the determinants for association with, integration into, and orientation of the protein in the outer envelope of chloroplasts. The insertion of OEP7 into the membrane is independent of outer membrane channel proteins and can be reconstituted with the use of protein-free liposomes. In situ, the binding of OEP7 to the membrane surface is not driven by electrostatic interaction because reduction of phosphatidylglycerol or phosphatidylinositol did not reduce the association with the liposomes. The positively charged amino acids flanking the transmembrane domain at the C terminus are essential to retain the native N(in)-C(out) orientation during insertion into chloroplasts. OEP7 inserts with reversed orientation into liposomes containing the average lipid composition of the outer envelopes. The native like N(in)-C(out) orientation is achieved by reduction of the phoshpatidylglycerol concentration mimicking the composition of the outer leaflet of the outer envelope of chloroplasts. We conclude that the unique lipid composition of the outer leaflet due to lipid asymmetry of the outer envelope is essential for the correct topology of OEP7.
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Daubenberger CA, Salomon M, Vecino W, Hübner B, Troll H, Rodriques R, Patarroyo ME, Pluschke G. Functional and structural similarity of V gamma 9V delta 2 T cells in humans and Aotus monkeys, a primate infection model for Plasmodium falciparum malaria. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:6421-30. [PMID: 11714808 DOI: 10.4049/jimmunol.167.11.6421] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Gammadelta T cells are implicated to play crucial roles during early immune responses to pathogens. A subset of human gammadelta T cells carrying the Vgamma9Vdelta2 TCR recognize small, phosphorylated nonpeptidic Ags. However, the precise role of these cells and the ligands recognized in human immune responses against pathogens remains unclear because of the lack of suitable animal models. We have analyzed the reactivity of spleen cells of the New World monkey Aotus nancymaae against isopentenyl pyrophosphate (IPP), a phosphorylated microbial metabolite selectively activating Vgamma9Vdelta2 T cells. Spleen cells were stimulated by IPP and the expanding cell population expressed the Vgamma9 TCR. TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated cells of Aotus were analyzed by RT-PCR and DNA sequencing. The TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated Aotus and human gammadelta T cells were similar with respect to 1) TCR gene segment usage, 2) a high degree of germline sequence homology of the TCR gene segments used, and 3) the diversity of the CDR3 regions. Phylogenetic analysis of human, Pan troglodytes, and A. nancymaae TRGV gene segments showed that the interspecies differences are smaller than the intraspecies differences with TRGV9 gene segments located on a distinct clade of the phylogenetic tree. The structural and functional conservation of Vgamma9Vdelta2 T cells in A. nancymaae and humans implicates a functionally important and evolutionary conserved mechanism of recognition of phosphorylated microbial metabolites.
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MESH Headings
- Amino Acid Sequence
- Animals
- Aotidae
- Base Sequence
- Cells, Cultured
- Disease Models, Animal
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/immunology
- Gene Rearrangement, delta-Chain T-Cell Antigen Receptor/drug effects
- Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor/drug effects
- Hemiterpenes
- Humans
- Immunoglobulin Joining Region/genetics
- Immunoglobulin Variable Region/genetics
- Interferon-gamma/biosynthesis
- Interferon-gamma/genetics
- Lymphocyte Activation/drug effects
- Malaria, Falciparum/immunology
- Malaria, Falciparum/metabolism
- Molecular Sequence Data
- Organophosphorus Compounds/pharmacology
- Pan troglodytes
- Receptors, Antigen, T-Cell, gamma-delta/chemistry
- Receptors, Antigen, T-Cell, gamma-delta/drug effects
- Receptors, Antigen, T-Cell, gamma-delta/physiology
- Sequence Analysis, DNA
- T-Lymphocyte Subsets/drug effects
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
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Salomon M, Eisenreich W, Dürr H, Schleicher E, Knieb E, Massey V, Rüdiger W, Müller F, Bacher A, Richter G. An optomechanical transducer in the blue light receptor phototropin from Avena sativa. Proc Natl Acad Sci U S A 2001; 98:12357-61. [PMID: 11606742 PMCID: PMC60058 DOI: 10.1073/pnas.221455298] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2001] [Indexed: 01/08/2023] Open
Abstract
The PHOT1 (NPH1) gene from Avena sativa specifies the blue light receptor for phototropism, phototropin, which comprises two FMN-binding LOV domains and a serine/threonine protein kinase domain. Light exposure is conducive to autophosphorylation of the protein kinase domain. We have reconstituted a recombinant LOV2 domain of A. sativa phototropin with various (13)C/(15)N-labeled isotopomers of the cofactor, FMN. The reconstituted protein samples were analyzed by NMR spectroscopy under dark and light conditions. Blue light irradiation is shown to result in the addition of a thiol group (cysteine 450) to the 4a position of the FMN chromophore. The adduct reverts spontaneously in the dark by elimination. The light-driven flavin adduct formation results in conformational modification, which was diagnosed by (1)H and (31)P NMR spectroscopy. This conformational change is proposed to initiate the transmission of the light signal via conformational modulation of the protein kinase domain conducive to autophosphorylation of NPH1.
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Briggs WR, Christie JM, Salomon M. Phototropins: a new family of flavin-binding blue light receptors in plants. Antioxid Redox Signal 2001; 3:775-88. [PMID: 11761327 DOI: 10.1089/15230860152664975] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Phototropin is the designation originally assigned to a recently characterized chromoprotein that serves as a photoreceptor for phototropism. Phototropin is a light-activated autophosphorylating serine/threonine kinase that binds two flavin mononucleotide (FMN) molecules that function as blue light-absorbing chromophores. Each FMN molecule is bound in a rigid binding pocket within specialized PAS (PER-ARNT-SIM superfamily) domains, known as LOV (light, oxygen, or voltage) domains. This article reviews the detailed photobiological and biochemical characterization of the light-activated phosphorylation reaction of phototropin and follows the sequence of events leading to the cloning, sequencing, and characterization of the gene and the subsequent biochemical characterization of its encoded protein. It then considers recent biochemical and photochemical evidence that light activation of phototropin involves the formation of a cysteinyl adduct at the C(4a) position of the FMN chromophores. Adduct formation causes a major conformational change in the chromophores and a possible conformational change in the protein moiety as well. The review concludes with a brief discussion of the evidence for a second phototropin-like protein in Arabidopsis and rice. Possible roles for this photoreceptor are discussed.
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Briggs WR, Beck CF, Cashmore AR, Christie JM, Hughes J, Jarillo JA, Kagawa T, Kanegae H, Liscum E, Nagatani A, Okada K, Salomon M, Rüdiger W, Sakai T, Takano M, Wada M, Watson JC. The phototropin family of photoreceptors. THE PLANT CELL 2001; 13:993-7. [PMID: 11424903 PMCID: PMC1464709 DOI: 10.1105/tpc.13.5.993] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
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Salomon M, Mayzaud P, Buchholz F. Studies on metabolic properties in the Northern Krill, Meganyctiphanes norvegica (Crustacea, euphausiacea): influence of nutrition and season on pyruvate kinase. Comp Biochem Physiol A Mol Integr Physiol 2000; 127:505-14. [PMID: 11154947 DOI: 10.1016/s1095-6433(00)00281-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The specific activity and the kinetic properties of partly purified pyruvate kinase (PK) (EC 2.7.1.40) from the Northern Krill, Meganyctiphanes norvegica, were investigated in relation to varying food resources. In order to evaluate the effect of starvation on the total energy metabolism, the respiration rates of fed and unfed krill were determined. The FPLC-elution profile of PK displayed two distinct peaks - PK I and II. The first isoform represented 80% of the total PK activity in the organism, and 20% was contributed by the second isoform. PK I was inhibited by ATP but was not influenced by fructose-1,6-bisphosphate (FBP). In contrast, PK II showed ATP inhibition and up to 2.5-fold increased activity by addition of 17 micromol.l(-1) FBP. The Michaelis-Menten constants of both isoforms were 2-10-fold higher for ADP than for phosphoenolpyruvate (PEP). Alanine showed no regulatory effect on PK I and II. In specimens starved for 7 days oxygen consumption decreased by 20%. Neither the feeding experiments nor the animals captured in the field during low and high productive seasons indicate that PK properties of M. norvegica are modified in relation to food supply. Accordingly, alternative mechanisms are involved in the depression of the metabolic rate in terms of oxygen consumption.
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Panero S, Satolli D, Salomon M, Scrosati B. A new type of lithium-ion cell based on the Li4Ti5O12/Li2Co0.4Fe0.4Mn3.2O8 high-voltage, electrode combination. Electrochem commun 2000. [DOI: 10.1016/s1388-2481(00)00127-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Salomon M, Christie JM, Knieb E, Lempert U, Briggs WR. Photochemical and mutational analysis of the FMN-binding domains of the plant blue light receptor, phototropin. Biochemistry 2000; 39:9401-10. [PMID: 10924135 DOI: 10.1021/bi000585+] [Citation(s) in RCA: 420] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The plant photoreceptor phototropin is an autophosphorylating serine-threonine protein kinase activated by UV-A/blue light. Two domains, LOV1 and LOV2, members of the PAS domain superfamily, mediate light sensing by phototropin. Heterologous expression studies have shown that both domains function as FMN-binding sites. Although three plant blue light photoreceptors, cry1, cry2, and phototropin, have been identified to date, the photochemical reactions underlying photoactivation of these light sensors have not been described so far. Herein, we demonstrate that the LOV domains of Avena sativa phototropin undergo a self-contained photocycle characterized by a loss of blue light absorbance in response to light and a spontaneous recovery of the blue light-absorbing form in the dark. Rate constants and quantum efficiencies for the photoreactions indicate that LOV1 exhibits a lower photosensitivity than LOV2. The spectral properties of the photoproduct produced for both LOV domains are unrelated to those found for photoreduced flavins and flavoproteins, but are consistent with those of a flavin-cysteinyl adduct. Flavin-thiol adducts are generally short-lifetime reaction intermediates formed during the flavoprotein-catalyzed reduction of protein disulfides. By site-directed mutagenesis, we have identified several amino acid residues within the putative chromophore binding site of LOV1 and LOV2 that appear to be important for FMN binding and/or the photochemical reactivity. Among those is Cys39, which plays an important role in the photochemical reaction of the LOV domains. Replacement of Cys39 with Ala abolished the photochemical reactions of both LOV domains. We therefore propose that light sensing by the phototropin LOV domains occurs via the formation of a stable adduct between the FMN chromophore and Cys39.
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Salomon M, Christie JM, Knieb E, Lempert U, Briggs WR. Photochemical and mutational analysis of the FMN-binding domains of the plant blue light receptor, phototropin. Biochemistry 2000. [PMID: 10924135 DOI: 10.1021/bi000585] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The plant photoreceptor phototropin is an autophosphorylating serine-threonine protein kinase activated by UV-A/blue light. Two domains, LOV1 and LOV2, members of the PAS domain superfamily, mediate light sensing by phototropin. Heterologous expression studies have shown that both domains function as FMN-binding sites. Although three plant blue light photoreceptors, cry1, cry2, and phototropin, have been identified to date, the photochemical reactions underlying photoactivation of these light sensors have not been described so far. Herein, we demonstrate that the LOV domains of Avena sativa phototropin undergo a self-contained photocycle characterized by a loss of blue light absorbance in response to light and a spontaneous recovery of the blue light-absorbing form in the dark. Rate constants and quantum efficiencies for the photoreactions indicate that LOV1 exhibits a lower photosensitivity than LOV2. The spectral properties of the photoproduct produced for both LOV domains are unrelated to those found for photoreduced flavins and flavoproteins, but are consistent with those of a flavin-cysteinyl adduct. Flavin-thiol adducts are generally short-lifetime reaction intermediates formed during the flavoprotein-catalyzed reduction of protein disulfides. By site-directed mutagenesis, we have identified several amino acid residues within the putative chromophore binding site of LOV1 and LOV2 that appear to be important for FMN binding and/or the photochemical reactivity. Among those is Cys39, which plays an important role in the photochemical reaction of the LOV domains. Replacement of Cys39 with Ala abolished the photochemical reactions of both LOV domains. We therefore propose that light sensing by the phototropin LOV domains occurs via the formation of a stable adduct between the FMN chromophore and Cys39.
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Salomon M, Buchholz F. Effects of temperature on the respiration rates and the kinetics of citrate synthase in two species of Idotea (Isopoda, Crustacea). Comp Biochem Physiol B Biochem Mol Biol 2000; 125:71-81. [PMID: 10840643 DOI: 10.1016/s0305-0491(99)00158-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The two species of isopods, Idotea baltica (Pallas) and Idotea emarginata (Fabricius), co-occur frequently near Helgoland, North Sea, occupying different ecological niches. Respiration rates and kinetic properties of citrate synthase (CS) were compared in these species in order to identify possible mechanisms of temperature adaptation. Specimens were acclimated to 5 and 15 degrees C prior to further investigations. Respiration rates were measured under normoxic conditions at 5, 10 and 15 degrees C. CS was partly purified chromatographically and influences of temperature, pH, substrate saturation and ATP-concentration on enzyme activity were examined. In both species, rising temperatures led to linearly increasing oxygen consumption, with estimated Q10 values between 3.2 and 4.2. Only I. baltica showed an effect of short term acclimation: warm adapted animals had always higher respiration rates than cold adapted ones. In I. emarginata, the acclimation temperature had no effect on oxygen consumption. Furthermore, its CS slightly indicates higher affinity to oxaloacetic acid when specimens were adapted to 15 degrees C compared to those maintained at 5 degrees C. Any effect of the experimental temperature on CS in I. baltica was negligible. The results are discussed in view of the different habitats occupied by the species compared.
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Christie JM, Salomon M, Nozue K, Wada M, Briggs WR. LOV (light, oxygen, or voltage) domains of the blue-light photoreceptor phototropin (nph1): binding sites for the chromophore flavin mononucleotide. Proc Natl Acad Sci U S A 1999; 96:8779-83. [PMID: 10411952 PMCID: PMC17593 DOI: 10.1073/pnas.96.15.8779] [Citation(s) in RCA: 457] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phototropism, the bending response of plant organs to or away from a directional light source, is one of the best studied blue light responses in plants. Although phototropism has been studied for more than a century, recent advances have improved our understanding of the underlying signaling mechanisms involved. The NPH1 gene of Arabidopsis thaliana encodes a blue light-dependent autophosphorylating protein kinase with the properties of a photoreceptor for phototropism. NPH1 apoprotein noncovalently binds FMN to form the holoprotein nph1. The N-terminal region of the protein contains two LOV (light, oxygen, or voltage) domains that share homology with sensor proteins from a diverse group of organisms. These include the bacterial proteins NIFL and AER, both of which bind FAD, and the phy3 photoreceptor from Adiantium capillus-veneris. The LOV domain has therefore been proposed to reflect a flavin-binding site, regulating nph1 kinase activity in response to blue light-induced redox changes. Herein we demonstrate that the LOV domains of two nph1 proteins and phy3 bind stoichiometric amounts of FMN when expressed in Escherichia coli. The spectral properties of the chromopeptides are similar to the action spectrum for phototropism, implying that the LOV domain binds FMN to function as a light sensor. Thus, our findings support the earlier model that nph1 is a dual-chromophoric flavoprotein photoreceptor regulating phototropic responses in higher plants. We therefore propose the name phototropin to designate the nph1 holoprotein.
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Salomon M. How do you price a used device? MATERIALS MANAGEMENT IN HEALTH CARE 1998; 7:54. [PMID: 10187362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Salomon M, Zacherl M, Rudiger W. Asymmetric, blue light-dependent phosphorylation of a 116-kilodalton plasma membrane protein can be correlated with the first- and second-positive phototropic curvature of oat coleoptiles. PLANT PHYSIOLOGY 1997; 115:485-91. [PMID: 11536817 PMCID: PMC158506 DOI: 10.1104/pp.115.2.485] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The possible correlation between blue light-dependent phosphorylation of a 116-kD protein and phototropic responses of etiolated oat (Avena sativa L.) seedlings was tested by a micromethod for protein phosphorylation. Quantitation of the basipetal distribution of this protein showed that the in vitro 32p phosphorylation values declined exponentially from tip to node, with more than 50% of the total label being found in the uppermost 5 mm. Nonsaturating preirradiation of the coleoptiles in vivo resulted in partial phosphorylation with endogenous ATP. Subsequent in vitro phosphorylation under saturating irradiation allowed the determination of the degree of in vivo phosphorylation. Unilateral preirradiation resulted in higher in vivo phosphorylation on the irradiated than on the shaded side of the coleoptile. The fluence-response curve for the difference in phosphorylation between both sides of the coleoptile resembles the fluence-response curve for first-positive phototropic curvature, although it is shifted by two orders of magnitude to higher fluences. Possible reasons for this shift are discussed. In the coleoptile base the phosphorylation gradient across the coleoptile becomes larger with increasing time of irradiation at a constant fluence. Thus, phosphorylation of the 116-kD protein, in accordance with second-positive phototropic curvature, does not obey the Bunsen-Roscoe reciprocity law.
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Salomon M, Zacherl M, Luff L, Rudiger W. Exposure of oat seedlings to blue light results in amplified phosphorylation of the putative photoreceptor for phototropism and in higher sensitivity of the plants to phototropic stimulation. PLANT PHYSIOLOGY 1997; 115:493-500. [PMID: 11536818 PMCID: PMC158507 DOI: 10.1104/pp.115.2.493] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Dark recovery of blue light-induced in vitro phosphorylation in oat (Avena sativa L.) seedlings after in vivo preirradiation with blue light revealed different recovery kinetics for the coleoptile base and tip. Although, in both cases, maximum in vitro phosphorylation was observed 90 min after in vivo blue light treatment, the phosphorylation levels for the entire base were about 3-fold higher than those found in nonpreirradiated plants. The tip response only slightly exceeded that of the dark controls. The fluence applied during preirradiation determined the extent of the increase in phosphorylation. Consequently, unilateral irradiation and subsequent dark incubation resulted in a more pronounced increase in phosphorylation in the irradiated than in the shaded side of the coleoptile base. Furthermore, blue light-irradiation conditions, known to induce neither first- nor second-positive curvature in nonpreirradiated plants, stimulated both asymmetric distribution of protein phosphorylation and second-positive phototropic curvature in the coleoptile base when administered to blue light-pretreated plants. Based on these data, we conclude that photosensitivity of the coleoptile base increases upon exposure to blue light in a time-and fluence-dependent manner, providing an excellent explanation of the invalidity of the Bunsen-Roscoe reciprocity law for second-positive phototropism.
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Khoury AE, Salomon M, Doche R, Soboh F, Ackerley C, Jayanthi R, McLorie GA, Mittelman MW. Stone formation after augmentation cystoplasty: the role of intestinal mucus. J Urol 1997; 158:1133-7. [PMID: 9258156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE We evaluated the role of mucus in urine after bladder augmentation and hypothesize that mucus acts as a possible etiological factor in stone formation. MATERIALS AND METHODS Mucus was collected via centrifugation from the 24-hour urine specimens of 8 stone forming and 10 nonstone forming patients who were randomly selected from our augmentation population. The mucus and stones were lyophilized, and then analyzed via scanning electron microscopy and energy dispersive x-ray spectrometry for calcium, phosphate, magnesium and sodium. The 24-hour urine collections were also analyzed to determine any metabolic differences between the 2 groups. RESULTS Scanning electron microscopy and energy dispersive x-ray spectrometry spectra showed increased calcium, phosphate, and magnesium, and significantly higher (p < 0.05) calcium-to-phosphate ratios in the mucus of stone versus nonstone forming patients. Of the 8 stones examined all had viscous fluid (mucus) centers rich in calcium, phosphate and magnesium. Calcium-to-phosphate ratios in the corresponding mucus recovered from stone centers were similarly high. Urinary citrate levels were low in both groups, and calcium, phosphate and magnesium were within normal ranges. CONCLUSIONS Mucus appears to have an important role in the genesis of bladder stones after augmentation, possibly acting as a nidus. Metabolic changes following augmentation were similar in stone and nonstone forming populations. Our data suggest that mucous calcium-to-phosphate ratios may be predictive of future stone formation. Furthermore, there may be a benefit in instituting more aggressive measures aimed at clearing mucus from the bladder.
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Salomon M, Zacherl M, Rudiger W. Changes in blue-light-dependent protein phosphorylation during the early development of etiolated oat seedlings. PLANTA 1996; 199:336-342. [PMID: 11541069 DOI: 10.1007/bf00195724] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Blue light induced the phosphorylation of a 116-kDa plasma-membrane-associated protein in dark-grown seedlings from Avena sativa L. The response was restricted to the phototropically sensitive tissue of the coleoptile tip. Surprisingly, this protein showed different properties in membrane preparations from plants that were grown for 3 d than in those from 5-d-old seedlings. In contrast to the younger coleoptiles, in 5-d-old seedlings phosphorylation of the 116-kDa protein depended strictly on the addition of Triton X-100 or other non-ionic detergents and was not abolished when the membranes were pretreated with trypsin. These latter membranes were also characterized by the appearance of two additional blue-light-regulated phosphoproteins of slightly lower molecular masses, exhibiting properties similar to the 116-kDa protein from 3-d-old plants. The data, together with solubilization studies, indicate that the 116-kDa protein is strongly membrane-bound only at the very beginning of seedling development and becomes more loosely associated in the course of coleoptile growth. In addition, we demonstrate that the capacity of the light-activated photoreceptor to recover photosensitivity in the dark also can occur under in-vitro conditions.
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