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David Ordóñez - One of the best experts on this subject based on the ideXlab platform.

  • Putrescine active uptake system in the Trypanosomatid Crithidia fasciculata.
    Biological chemistry Hoppe-Seyler, 1996
    Co-Authors: Mar Calonge, Juan C. Cubrı́a, Rafael Balaña-fouce, David Ordóñez
    Abstract:

    Using the insect Trypanosomatid Crithidia fasciculata as a model parasite of mammalian pathogenic flagellates, i.e. Leishmania and Trypanosoma spp., we have studied the kinetic and regulatory characteristics of the polyamine uptake system. Putrescine transport was age-dependent with maximum expression values at the proliferative logarithmic phase. Putrescine transport in Crithidia fasciculata was energy-dependent and against a putrescine concentration gradient. The integrity of the membrane sulfhydryl groups was absolutely required for optimum transport rates. The specificity of this mechanism was studied in the presence of a series of different chain length aliphatic diamines, showing the high specificity for putrescine and the poor effect of this series at the highest concentration analyzed as well as the higher polyamines spermidine and spermine. Finally, the well-known inhibitor of polyamine biosynthesis, DFMO, led to an upward regulation of putrescine uptake correlating with the depletion of intracellular polyamine pool. In addition, the presence of high concentrations of putrescine in the culture medium produced a downward regulation of this system.

  • Structural determinants of putrescine uptake inhibition produced by cationic diamidines in the model of trypanosomatid Crithidia fasciculata.
    Biological chemistry, 1996
    Co-Authors: Isabel Navas, Rafael Balaña-fouce, Antonio J. García-fernández, Raoul A. Johnson, Rosa M. Reguera, David Ordóñez
    Abstract:

    The effect of a heterologous series of cationic diamidines has been tested on cell growth and polyamine uptake on the model of insect Trypanosomatid Crithidia fasciculata. The maximum inhibitory effect on both parameters was found for pentamidine and dibromopropamidine, which exhibit a longer distance between amino and imino substituents. A minimum inhibitory effect was found with amicarbalide. A good relationship was obtained when the distance between amino moieties was plotted versus the inhibitory effect on putrescine uptake, suggesting a role of this structural property on polyamine transport in Crithidia fasciculata. In addition, a similar correlation was obtained for another Trypanosomatid parasite, Leishmania infantum.

  • Effects of cationic diamidines on polyamine metabolism in the trypanosomatid Crithidia fasciculata.
    Life sciences, 1996
    Co-Authors: María M. Calonge, Rafael Balaña-fouce, Alaa E. Bayoumi, J.carlos Cubría, David Ordóñez
    Abstract:

    Abstract The effect of a series of five recently synthesized cat ionic diamidines on cell proliferation and polyamine metabolism was studied on cultures of the model Trypanosomatid Crithidia fasciculata . Compounds displaying two arylic moieties (CGP039937A and CGP040215A) were ten fold more cytostatic than those displaying only one arylic residue (CGP033829A, CGP035753A and CGP036958A). The depletion of intracellular polyamine, putrescine and spermidine, pools and the effect of these compounds on S-adenosylmethionine decarboxylase and putrescine uptake suggest the requirement of two arylic groups in their chemical structure to obtain measurable effects on both polyamine metabolism and cell growth.

Lo Persson - One of the best experts on this subject based on the ideXlab platform.

  • Extremely rapid turnover of S-adenosylmethionine decarboxylase in Crithidia fasciculata.
    FEBS letters, 2003
    Co-Authors: Sima Nasizadeh, Lo Persson
    Abstract:

    The activity of S-adenosylmethionine decarboxylase (AdoMetDC) in Crithidia fasciculata was shown to be correlated to the growth of the parasite. An increase in activity was observed during exponential growth. Inhibition of protein synthesis induced an extremely rapid decay of AdoMetDC activity. The half-life of the enzyme was estimated to be about 3 min, which is the shortest half-life ever recorded for an eukaryotic AdoMetDC. The reduction in AdoMetDC activity was correlated with a decrease in AdoMetDC protein content, demonstrating a rapid turnover of the enzyme. No polyamine-mediated feedback regulation of AdoMetDC was observed in the parasite.

  • Extremely rapid turnover of S‐adenosylmethionine decarboxylase in Crithidia fasciculata
    FEBS Letters, 2003
    Co-Authors: Sima Nasizadeh, Lo Persson
    Abstract:

    The activity of S-adenosylmethionine decarboxylase (AdoMetDC) in Crithidia fasciculata was shown to be correlated to the growth of the parasite. An increase in activity was observed during exponential growth. Inhibition of protein synthesis induced an extremely rapid decay of AdoMetDC activity. The half-life of the enzyme was estimated to be about 3 min, which is the shortest half-life ever recorded for an eukaryotic AdoMetDC. The reduction in AdoMetDC activity was correlated with a decrease in AdoMetDC protein content, demonstrating a rapid turnover of the enzyme. No polyamine-mediated feedback regulation of AdoMetDC was observed in the parasite.

Paul T. Englund - One of the best experts on this subject based on the ideXlab platform.

  • kinetoplast maxicircle dna replication in Crithidia fasciculata and trypanosoma brucei
    Molecular and Cellular Biology, 1995
    Co-Authors: Laura Rocco Carpenter, Paul T. Englund
    Abstract:

    Kinetoplast DNA, the mitochondrial DNA of trypanosomatids, is composed of several thousand minicircles and a few dozen maxicircles, all of which are topologically interlocked in a giant network. We have studied the replication of maxicircle DNA, using electron microscopy to analyze replication intermediates from both Crithidia fasciculata and Trypanosoma brucei. Replication intermediates were stabilized against branch migration by introducing DNA interstrand cross-links in vivo with 4,5',8-trimethylpsoralen and UV radiation. Electron microscopy of individual maxicircles resulting from a topoisomerase II decatenation of kinetoplast DNA networks revealed intact maxicircle theta structures. Analysis of maxicircle DNA linearized by restriction enzyme cleavage revealed branched replication intermediates derived from theta structures. Measurements of the linearized branched molecules in both parasites indicate that replication initiates in the variable region (a noncoding segment characterized by repetitive sequences) and proceeds unidirectionally, clockwise on the standard map.

  • A mitochondrial heat shock protein from Crithidia fasciculata.
    Molecular and biochemical parasitology, 1993
    Co-Authors: Philip N. Effron, A F Torri, David M. Engman, John E. Donelson, Paul T. Englund
    Abstract:

    MCP72 is a mitochondrial hsp70 protein from the trypanosomatid Crithidia fasciculata. An MCP72 cDNA clone was isolated from a C. fasciculata cDNA library by screening with antiserum specific for the homologous protein of Trypanosoma cruzi [9]. The MCP72 cDNA encodes a polypeptide of 663 amino acids which is 84% identical to the Trypanosoma cruzi protein and 56% identical to the Escherichia coli hsp70 protein DnaK. MCP72 is less similar to other hsp70 proteins. Native MCP72 was purified to homogeneity by ATP-agarose affinity chromatography. Comparison of its N-terminal amino acid sequence with that deduced from the cDNA sequence shows that 20 amino acid residues had been cleaved from the N-terminus; this sequence probably represents a mitochondrial import signal which is cleaved during translocation into the mitochondrion. Fluorescence microscopy, using antibodies specific for MCP72, indicates that the protein is concentrated in a region of the mitochondrial matrix which surrounds the kinetoplast.

  • Purification of a mitochondrial DNA polymerase from Crithidia fasciculata.
    The Journal of biological chemistry, 1992
    Co-Authors: A F Torri, Paul T. Englund
    Abstract:

    Abstract The mitochondrial DNA polymerase from Crithidia fasciculata has been purified to near homogeneity. SDS-PAGE analysis of the purified enzyme reveals a single polypeptide with a molecular weight of approximately 43,000. The protein is basic, with an isoelectric point between 7.6-8.0. Its Stokes radius of 22 A and its sedimentation coefficient of 4.1 S suggest a native molecular weight of 38,000, indicating that the protein is a monomer under our experimental conditions. Western blots and immunoprecipitations of crude extracts reveal a cross-reacting protein of 48 kDa, suggesting that the purified enzyme may be an enzymatically active proteolytic product. The mitochondrial origin of the polymerase was confirmed by cell fractionation. Our results indicate that the C. fasciculata enzyme may be among the smallest known mitochondrial polymerases.

Sima Nasizadeh - One of the best experts on this subject based on the ideXlab platform.

  • Extremely rapid turnover of S-adenosylmethionine decarboxylase in Crithidia fasciculata.
    FEBS letters, 2003
    Co-Authors: Sima Nasizadeh, Lo Persson
    Abstract:

    The activity of S-adenosylmethionine decarboxylase (AdoMetDC) in Crithidia fasciculata was shown to be correlated to the growth of the parasite. An increase in activity was observed during exponential growth. Inhibition of protein synthesis induced an extremely rapid decay of AdoMetDC activity. The half-life of the enzyme was estimated to be about 3 min, which is the shortest half-life ever recorded for an eukaryotic AdoMetDC. The reduction in AdoMetDC activity was correlated with a decrease in AdoMetDC protein content, demonstrating a rapid turnover of the enzyme. No polyamine-mediated feedback regulation of AdoMetDC was observed in the parasite.

  • Extremely rapid turnover of S‐adenosylmethionine decarboxylase in Crithidia fasciculata
    FEBS Letters, 2003
    Co-Authors: Sima Nasizadeh, Lo Persson
    Abstract:

    The activity of S-adenosylmethionine decarboxylase (AdoMetDC) in Crithidia fasciculata was shown to be correlated to the growth of the parasite. An increase in activity was observed during exponential growth. Inhibition of protein synthesis induced an extremely rapid decay of AdoMetDC activity. The half-life of the enzyme was estimated to be about 3 min, which is the shortest half-life ever recorded for an eukaryotic AdoMetDC. The reduction in AdoMetDC activity was correlated with a decrease in AdoMetDC protein content, demonstrating a rapid turnover of the enzyme. No polyamine-mediated feedback regulation of AdoMetDC was observed in the parasite.

Rafael Balaña-fouce - One of the best experts on this subject based on the ideXlab platform.

  • Putrescine active uptake system in the Trypanosomatid Crithidia fasciculata.
    Biological chemistry Hoppe-Seyler, 1996
    Co-Authors: Mar Calonge, Juan C. Cubrı́a, Rafael Balaña-fouce, David Ordóñez
    Abstract:

    Using the insect Trypanosomatid Crithidia fasciculata as a model parasite of mammalian pathogenic flagellates, i.e. Leishmania and Trypanosoma spp., we have studied the kinetic and regulatory characteristics of the polyamine uptake system. Putrescine transport was age-dependent with maximum expression values at the proliferative logarithmic phase. Putrescine transport in Crithidia fasciculata was energy-dependent and against a putrescine concentration gradient. The integrity of the membrane sulfhydryl groups was absolutely required for optimum transport rates. The specificity of this mechanism was studied in the presence of a series of different chain length aliphatic diamines, showing the high specificity for putrescine and the poor effect of this series at the highest concentration analyzed as well as the higher polyamines spermidine and spermine. Finally, the well-known inhibitor of polyamine biosynthesis, DFMO, led to an upward regulation of putrescine uptake correlating with the depletion of intracellular polyamine pool. In addition, the presence of high concentrations of putrescine in the culture medium produced a downward regulation of this system.

  • Structural determinants of putrescine uptake inhibition produced by cationic diamidines in the model of trypanosomatid Crithidia fasciculata.
    Biological chemistry, 1996
    Co-Authors: Isabel Navas, Rafael Balaña-fouce, Antonio J. García-fernández, Raoul A. Johnson, Rosa M. Reguera, David Ordóñez
    Abstract:

    The effect of a heterologous series of cationic diamidines has been tested on cell growth and polyamine uptake on the model of insect Trypanosomatid Crithidia fasciculata. The maximum inhibitory effect on both parameters was found for pentamidine and dibromopropamidine, which exhibit a longer distance between amino and imino substituents. A minimum inhibitory effect was found with amicarbalide. A good relationship was obtained when the distance between amino moieties was plotted versus the inhibitory effect on putrescine uptake, suggesting a role of this structural property on polyamine transport in Crithidia fasciculata. In addition, a similar correlation was obtained for another Trypanosomatid parasite, Leishmania infantum.

  • Effects of cationic diamidines on polyamine metabolism in the trypanosomatid Crithidia fasciculata.
    Life sciences, 1996
    Co-Authors: María M. Calonge, Rafael Balaña-fouce, Alaa E. Bayoumi, J.carlos Cubría, David Ordóñez
    Abstract:

    Abstract The effect of a series of five recently synthesized cat ionic diamidines on cell proliferation and polyamine metabolism was studied on cultures of the model Trypanosomatid Crithidia fasciculata . Compounds displaying two arylic moieties (CGP039937A and CGP040215A) were ten fold more cytostatic than those displaying only one arylic residue (CGP033829A, CGP035753A and CGP036958A). The depletion of intracellular polyamine, putrescine and spermidine, pools and the effect of these compounds on S-adenosylmethionine decarboxylase and putrescine uptake suggest the requirement of two arylic groups in their chemical structure to obtain measurable effects on both polyamine metabolism and cell growth.