Die Plant Science Student Conference (PSSC) wird seit 20 Jahren im jährlichen Wechsel von Studierenden der beiden Leibniz-Institute IPK und IPB organisiert. Im Interview erläutern Christina Wäsch (IPK) und Carolin Apel (IPB),…
Über 600 Gäste kamen am 4. Juli ans IPB zur Langen Nacht, die Wissen schafft, um bei unserem Wissenschafts-Quiz-Parcours viel Neues zu erfahren und ihre Kenntnisse unter Beweis zu stellen. Unser Programm in diesem Jahr…
Lorey, S.; Stöckel-Maschek, A.; Faust, J.; Brandt, W.; Stiebitz, B.; Gorrell, M. D.; Kähne, T.; Mrestani-Klaus, C.; Wrenger, S.; Reinhold, D.; Ansorge, S.; Neubert, K.;Different modes of dipeptidyl peptidase IV (CD26) inhibition by oligopeptides derived from the N-terminus of HIV-1 Tat indicate at least two inhibitor binding sitesEur. J. Biochem.2702147-2156(2003)DOI: 10.1046/j.1432-1033.2003.03568.x
Dipeptidyl peptidase IV (DP IV, CD26) plays an essential role in the activation and proliferation of lymphocytes, which is shown by the immunosuppressive effects of synthetic DP IV inhibitors. Similarly, both human immunodeficiency virus‐1 (HIV‐1) Tat protein and the N‐terminal peptide Tat(1–9) inhibit DP IV activity and T cell proliferation. Therefore, the N‐terminal amino acid sequence of HIV‐1 Tat is important for the inhibition of DP IV. Recently, we characterized the thromboxane A2 receptor peptide TXA2‐R(1–9), bearing the N‐terminal MWP sequence motif, as a potent DP IV inhibitor possibly playing a functional role during antigen presentation by inhibiting T cell‐expressed DP IV [Wrenger, S., Faust, J., Mrestani‐Klaus, C., Fengler, A., Stöckel‐Maschek, A., Lorey, S., Kähne, T., Brandt, W., Neubert, K., Ansorge, S. & Reinhold, D. (2000) J. Biol. Chem. 275 , 22180–22186]. Here, we demonstrate that amino acid substitutions at different positions of Tat(1–9) can result in a change of the inhibition type. Certain Tat(1–9)‐related peptides are found to be competitive, and others linear mixed‐type or parabolic mixed‐type inhibitors indicating different inhibitor binding sites on DP IV, at the active site and out of the active site. The parabolic mixed‐type mechanism, attributed to both non‐mutually exclusive inhibitor binding sites of the enzyme, is described in detail. From the kinetic investigations and molecular modeling experiments, possible interactions of the oligopeptides with specified amino acids of DP IV are suggested. These findings give new insights for the development of more potent and specific peptide‐based DP IV inhibitors. Such inhibitors could be useful for the treatment of autoimmune and inflammatory diseases.
Publikation
Wrenger, S.; Hoffmann, T.; Faust, J.; Mrestani-Klaus, C.; Brandt, W.; Neubert, K.; Kraft, M.; Olek, S.; Frank, R.; Ansorge, S.; Reinhold, D.;The N-terminal Structure of HIV-1 Tat Is Required for Suppression of CD26-dependent T Cell GrowthJ. Biol. Chem.27230283-30288(1997)DOI: 10.1074/jbc.272.48.30283
Evidence exists that the human immunodeficiency virus-1 (HIV-1) transactivator Tat occurs extracellularly and is involved in the immunosuppression of non-HIV-1-infected T cells of acquired immunodeficiency syndrome (AIDS) patients. The mechanism of this immunosuppressive activity of Tat has been controversially discussed. Interestingly, Tat binds to the T cell activation marker CD26, which has been shown to play a key role in the regulation of growth of lymphocytes and to inhibit its dipeptidyl peptidase IV (DP IV) activity. Here we show that the N-terminal nonapeptide MDPVDPNIE of Tat is a competitive inhibitor of DP IV and suppresses DNA synthesis of tetanus toxoid-stimulated peripheral blood mononuclear cells. Amino acid exchanges at positions 5 and 6 strongly weaken these effects.1H nuclear magnetic resonance and molecular dynamics simulations of Tat(1–9), I5-Tat(1–9), and L6-Tat(1–9) suggest a similar backbone conformation for Tat(1–9) and L6-Tat(1–9). The solution conformation of I5-Tat(1–9) considerably differs from the other two. However, Tat(1–9) fits into our previously proposed active site model of DP IV in contrast to I5-Tat(1–9) and L6-Tat(1–9). Conformational alterations with regard to the parent peptide and spatial hindrances between these both compounds and DP IV can explain the loss of inhibitory activity. Our data suggest that the N-terminal residues of HIV-1 Tat do interact directly with the active site of DP IV and that DP IV does mediate Tat’s immunosuppressive effects.