Q95070814
Dotaz
Zobrazit nápovědu
In 1959, P. Karlson and M. Lüscher introduced the term 'pheromone', broadly used nowadays for various chemicals involved in intraspecific communication. To demonstrate the term, they depicted the situation in termite societies, where king and queen inhibit the reproduction of nest-mates by an unknown chemical substance. Paradoxically, half a century later, neither the source nor the chemical identity of this 'royal' pheromone is known. In this study, we report for the first time the secretion of polar compounds of proteinaceous origin by functional reproductives in three termite species, Prorhinotermes simplex, Reticulitermes santonensis and Kalotermes flavicollis. Aqueous washes of functional reproductives contained sex-specific proteinaceous compounds, virtually absent in non-reproducing stages. Moreover, the presence of these compounds was clearly correlated with the age of reproductives and their reproductive status. We discuss the putative function of these substances in termite caste recognition and regulation.
- MeSH
- hmyzí proteiny chemie metabolismus MeSH
- Isoptera klasifikace fyziologie MeSH
- rozmnožování MeSH
- sociální hierarchie MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- uhlovodíky analýza metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Hepcidin is a major regulator of iron metabolism. Hepcidin-based therapeutics/diagnostics could play roles in hematology in the future, and thus, hepcidin transport is crucial to understand. In this study, we identify alpha2-macroglobulin (alpha2-M) as the specific hepcidin-binding molecule in blood. Interaction of 125I-hepcidin with alpha2-M was identified using fractionation of plasma proteins followed by native gradient polyacrylamide gel electrophoresis and mass spectrometry. Hepcidin binding to nonactivated alpha2-M displays high affinity (Kd 177 +/- 27 nM), whereas hepcidin binding to albumin was nonspecific and displayed nonsaturable kinetics. Surprisingly, the interaction of hepcidin with activated alpha2-M exhibited a classical sigmoidal binding curve demonstrating cooperative binding of 4 high-affinity (Kd 0.3 microM) hepcidin-binding sites. This property probably enables efficient sequestration of hepcidin and its subsequent release or inactivation that may be important for its effector functions. Because alpha2-M rapidly targets ligands to cells via receptor-mediated endocytosis, the binding of hepcidin to alpha2-M may influence its functions. In fact, the alpha2-M-hepcidin complex decreased ferroportin expression in J774 cells more effectively than hepcidin alone. The demonstration that alpha2-M is the hepcidin transporter could lead to better understanding of hepcidin physiology, methods for its sensitive measurement and the development of novel drugs for the treatment of iron-related diseases.
- MeSH
- 2D gelová elektroforéza MeSH
- alfa-makroglobuliny metabolismus MeSH
- gelová chromatografie MeSH
- kationické antimikrobiální peptidy metabolismus MeSH
- kultivované buňky MeSH
- lidé MeSH
- makrofágy cytologie metabolismus MeSH
- monocyty cytologie metabolismus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- proteiny přenášející kationty metabolismus MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- vazba proteinů MeSH
- western blotting MeSH
- železo metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Trichomonas vaginalis is one of a few eukaryotes that have been found to encode several homologues of flavodiiron proteins (FDPs). Widespread among anaerobic prokaryotes, these proteins are believed to function as oxygen and/or nitric oxide reductases to provide protection against oxidative/nitrosative stresses and host immune responses. One of the T. vaginalis FDP homologues is equipped with a hydrogenosomal targeting sequence and is expressed in the hydrogenosomes, oxygen-sensitive organelles that participate in carbohydrate metabolism and assemble iron-sulfur clusters. The bacterial homologues characterized thus far have been dimers or tetramers; the trichomonad protein is a dimer of identical 45-kDa subunits, each noncovalently binding one flavin mononucleotide. The protein reduces dioxygen to water but is unable to utilize nitric oxide as a substrate, similarly to its closest homologue from another human parasite Giardia intestinalis and related archaebacterial proteins. T. vaginalis FDP is able to accept electrons derived from pyruvate or NADH via ferredoxin and is proposed to play a role in the protection of hydrogenosomes against oxygen.
- MeSH
- ferredoxiny genetika chemie izolace a purifikace metabolismus MeSH
- financování organizované MeSH
- flavinmononukleotid metabolismus MeSH
- kyslík metabolismus MeSH
- molekulární sekvence - údaje MeSH
- organely enzymologie genetika chemie MeSH
- oxidoreduktasy genetika chemie izolace a purifikace metabolismus MeSH
- protozoální proteiny genetika izolace a purifikace metabolismus MeSH
- sekvence aminokyselin MeSH
- substrátová specifita MeSH
- Trichomonas vaginalis enzymologie genetika chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
The highly reduced mitochondria (mitosomes) of Giardia intestinalis are recently discovered organelles for which, it was suggested, iron-sulfur cluster assembly was their only conserved function. However, only an incomplete set of the components required for FeS cluster biogenesis was localized to the mitosomes. Via proteomic analysis of a mitosome-rich cellular fraction together with immunofluorescence microscopy, we identified a novel mitosomal protein homologous to monothiol glutaredoxins containing a CGFS motif at the active site. Sequence analysis revealed the presence of long nonconserved N-terminal extension of 77 amino acids, which was absent in the mature protein. Expression of the complete and N-terminally truncated forms of the glutaredoxin indicated that the extension is involved in glutaredoxin import into mitosomes. However, the mechanism of preprotein processing is unclear, as the mitosomal processing peptidase is unable to cleave this type of extension. The recombinant mature protein was shown to form a homodimeric structure, which binds a labile FeS cluster. The cluster is stabilized by glutathione and dithiothreitol. Phylogenetic analysis showed that giardial glutaredoxin is related to the mitochondrial monothiol glutaredoxins involved in FeS cluster assembly. The identification of a mitochondrial-type monothiol glutaredoxin in the mitosomes of G. intestinalis thus completes the mitosomal FeS cluster biosynthetic pathway and provides further evidence for the mitochondrial origin of these organelles.
Mitochondrial processing peptidases are heterodimeric enzymes (alpha/betaMPP) that play an essential role in mitochondrial biogenesis by recognizing and cleaving the targeting presequences of nuclear-encoded mitochondrial proteins. The two subunits are paralogues that probably evolved by duplication of a gene for a monomeric metallopeptidase from the endosymbiotic ancestor of mitochondria. Here, we characterize the MPP-like proteins from two important human parasites that contain highly reduced versions of mitochondria, the mitosomes of Giardia intestinalis and the hydrogenosomes of Trichomonas vaginalis. Our biochemical characterization of recombinant proteins showed that, contrary to a recent report, the Trichomonas processing peptidase functions efficiently as an alpha/beta heterodimer. By contrast, and so far uniquely among eukaryotes, the Giardia processing peptidase functions as a monomer comprising a single betaMPP-like catalytic subunit. The structure and surface charge distribution of the Giardia processing peptidase predicted from a 3-D protein model appear to have co-evolved with the properties of Giardia mitosomal targeting sequences, which, unlike classic mitochondrial targeting signals, are typically short and impoverished in positively charged residues. The majority of hydrogenosomal presequences resemble those of mitosomes, but longer, positively charged mitochondrial-type presequences were also identified, consistent with the retention of the Trichomonas alphaMPP-like subunit. Our computational and experimental/functional analyses reveal that the divergent processing peptidases of Giardia mitosomes and Trichomonas hydrogenosomes evolved from the same ancestral heterodimeric alpha/betaMPP metallopeptidase as did the classic mitochondrial enzyme. The unique monomeric structure of the Giardia enzyme, and the co-evolving properties of the Giardia enzyme and substrate, provide a compelling example of the power of reductive evolution to shape parasite biology.
- MeSH
- down regulace genetika MeSH
- fylogeneze MeSH
- genová dávka MeSH
- Giardia lamblia genetika metabolismus ultrastruktura MeSH
- glycin fyziologie genetika chemie MeSH
- metaloendopeptidasy genetika chemie metabolismus MeSH
- mitochondrie metabolismus MeSH
- multimerizace proteinu MeSH
- organely metabolismus MeSH
- podjednotky proteinů genetika MeSH
- posttranslační úpravy proteinů genetika MeSH
- proteinové domény bohaté na prolin fyziologie genetika MeSH
- řízená evoluce molekul MeSH
- sekvence aminokyselin MeSH
- transport proteinů MeSH
- Trichomonas vaginalis genetika metabolismus ultrastruktura MeSH
- vodík metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
- srovnávací studie MeSH
BACKGROUND: A series of juvenoid alcohols and their glycosidic derivatives (juvenogens), synthesized at the Institute of Organic Chemistry and Biochemistry in Prague, commercially used juvenoids and the natural derivatives of juvabione were evaluated for their systemic juvenilizing effect on the red firebug, Pyrrhocoris apterus L., and on the pea aphid, Acyrthosiphon pisum Harris. A life table response experiment was designed, and demographic characteristics were computed for a cohort of A. pisum following chronic exposure to a range of concentrations of the selected trans-isomer of carbamate juvenoid 8 applied via the broad bean (Vicia faba L.) root system. RESULTS: Using the ratio of topical and per os activities, promising effects were found in two alkyl beta-D-glucopyranosides (3 and 9) and the trans-isomer of carbamate juvenoid 8 in tests on P. apterus. In A. pisum, the highest systemic activity was found in tests with the trans-isomer of carbamate juvenoid 8. The longevity, the number of offspring per female and the number of offspring per reproducing female significantly decreased with concentrations of 0.05 mg mL(-1) and higher. While the net reproductive rate R(0) and the intrinsic rate of natural increase r(m) displayed similar trends, the generation time G varied slightly between 11.6 and 12.8 days. CONCLUSION: Expected systemic activity of glycosidic juvenogens in P. apterus was not confirmed by exposure of the pea aphid on broad bean treated with aqueous solutions of the compounds. Nevertheless, the carbamate juvenoid alcohol 8 displayed a considerable juvenilizing effect on A. pisum in screening tests. Furthermore, this compound indicated a sublethal effect as the realized fecundity U(x) decreased disproportionately to the age-specific survival L(x) with increased concentration. The population parameters are compared with the data in similar demographic studies and are discussed together with the possibilities of using the compounds of this structural type in practice. Society of Chemical Industry
Recent data suggest that frataxin plays a key role in eukaryote cellular iron metabolism, particularly in mitochondrial heme and iron-sulfur (FeS) cluster biosynthesis. We have now identified a frataxin homologue (T. vaginalis frataxin) from the human parasite Trichomonas vaginalis. Instead of mitochondria, this unicellular eukaryote possesses hydrogenosomes, peculiar organelles that produce hydrogen but nevertheless share common ancestry with mitochondria. T. vaginalis frataxin contains conserved residues implicated in iron binding, and in silico, it is predicted to form a typical alpha-beta sandwich motif. The short N-terminal extension of T. vaginalis frataxin resembles presequences that target proteins to hydrogenosomes, a prediction confirmed by the results of overexpression of T. vaginalis frataxin in T. vaginalis. When expressed in the mitochondria of a frataxin-deficient Saccharomyces cerevisiae strain, T. vaginalis frataxin partially restored defects in heme and FeS cluster biosynthesis. Although components of heme synthesis or heme-containing proteins have not been found in T. vaginalis to date, T. vaginalis frataxin was also shown to interact with S. cerevisiae ferrochelatase by using a Biacore assay. The discovery of conserved iron-metabolizing pathways in mitochondria and hydrogenosomes provides additional evidence not only of their common evolutionary history, but also of the fundamental importance of this pathway for eukaryotes.
- MeSH
- financování organizované MeSH
- genetická transkripce MeSH
- konzervovaná sekvence MeSH
- mitochondriální proteiny genetika metabolismus MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- organely metabolismus MeSH
- proteiny vázající železo genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- Trichomonas vaginalis genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
The S-adenosylhomocysteine hydrolase from the apicomplexan Cryptosporidium parvum (CpSAHH) has been characterized. CpSAHH is a single-copy, intronless gene of 1479 bp encoding a protein of 493 amino acids with a molecular mass of 55.6 kDa. Reverse transcriptase-polymerase chain reaction analysis confirmed that CpSAHH is expressed both in intracellular stages (in C. parvum-infected HCT-8 cells 24 h after infection) and in sporozoites. CpSAHH was expressed in Escherichia coli TB1 cells as a fusion with maltose-binding protein. The recombinant fusion was cleaved by Factor Xa and the enzymatic activity of both the fusion protein and the purified separated CpSAHH was measured. The enzymatic activity of CpSAHH was inhibited by d-eritadenine, S-DHPA and Ara-A.
- MeSH
- adenin analogy a deriváty farmakologie MeSH
- adenosylhomocysteinasa antagonisté a inhibitory genetika chemie metabolismus MeSH
- Cryptosporidium parvum enzymologie genetika MeSH
- Escherichia coli genetika MeSH
- exprese genu MeSH
- financování organizované MeSH
- introny MeSH
- messenger RNA biosyntéza genetika MeSH
- molekulární sekvence - údaje MeSH
- molekulová hmotnost MeSH
- rekombinantní fúzní proteiny analýza genetika izolace a purifikace metabolismus MeSH
- RNA protozoální biosyntéza genetika MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- vidarabin farmakologie MeSH
- vývojová regulace genové exprese MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
Two different types of juvenogens, biochemically targeted hormonogen compounds were tested for their potency to act as insect pest management agents. In the performed biological screening, wax-like esteric juvenogens (3-10) proved to be convenient agents for controlling blowfly and termites, and displayed species selectivity: cis-N-{2-[4-(2-butanoyloxycyclohexyl)methyl]phenoxy}ethyl carbamate (3) was highly active on blowfly (Neobellieria bullata), while trans-N-{2-[4-(2-hexadecanoyloxycyclohexyl)methyl]-phenoxy}ethyl carbamate (6) showed high activity on termite (Prorhinotermes simplex). Glycosidic juvenogens, isomeric N-{2-{4-{[2-(beta-D-galactopyranosyloxy)cyclohexyl]methyl}phenoxy}ethyl carbamates (13 and 14), were proved to act as systemic agents, suitable for protecting plants against phytophagous insects (e.g. aphids). Due to the prolonged action of juvenogens, which is connected with the sequential liberating of the biologically active molecule of the insect juvenile hormone bioanalog from the juvenogen molecule by means of enzymic systems of target insects and/or their host plants, more insect individuals can be treated by juvenogens, which are species-targeted structures due to their different physicochemical properties. The results achieved with both types of juvenogens were promising, concerning their final effect on the tested insect species, and the compounds 3-6, 9 (cis-(9Z)-N-{2-[4-(2-(octadec-9-enoyl)oxycyclohexyl)methyl]phenoxy}ethyl carbamate), 13 and 14 proved to represent convenient insect pest management agents for potential practical applications against different insect pests.
Residues of the insect growth regulator diflubenzuron were quantified on horse chestnut (Aesculus hippocastanum L.) leaves treated with a diflubenzuron 480 g litre(-1) SC, Dimilin. To analyse the samples, an analytical procedure was developed involving a simple extraction step followed by high-performance liquid chromatography on an octadecyl-modified silica column with methanol + 0.01 M ammonium acetate mobile phase. The results showed diflubenzuron to be highly stable on horse chestnut leaves; more than 4 months (127 days) after application, 38% (on average) of the insecticide still remained on/in the leaves. The data confirmed biological observations showing diflubenzuron's long-term efficacy against the horse chestnut leafminer, Cameraria ohridella Deschka and Dimić, which is the most important pest of the horse chestnut in Europe. The hypothesis of possible penetration of diflubenzuron into the leaf mass is explored and discussed.
