FEBS Letters
Volume 584, Issue 18 , Pages 4083-4088, 24 September 2010

Binding and catalysis of Humulus lupulus adenylate isopentenyltransferase for the synthesis of isopentenylated diadenosine polyphosphates

Edited by Ulf-Ingo Flügge

  • Hsing-Mao Chu

      Affiliations

    • Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
    • These authors have equal contribution.
    • ,
  • Feng-Yuan Chen

      Affiliations

    • Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
    • Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
    • These authors have equal contribution.
    • ,
  • Tzu-Ping Ko

      Affiliations

    • Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
    • ,
  • Andrew H.-J. Wang

      Affiliations

    • Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
    • Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
    • Corresponding Author InformationCorresponding author at: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan. Fax: +886 2 2788 2043.

Received 9 August 2010; received in revised form 26 August 2010; accepted 26 August 2010. published online 31 August 2010.

Abstract 

Various plant developmental processes involve phytohormones such as cytokinins. Isopentenyltransferase (IPT) reaction is the key rate-limiting step in cytokinin biosynthesis that transfers the isopentenyl (iP) group from dimethylallyl diphosphate to the N6-amino group of adenine. Here, a series of diadenosine polyphosphates (ApnA) were screened as possible substrates of IPT, among which diadenosine tetraphosphate, diadenosine pentaphosphate and diadenosine hexaphosphate showed higher affinity than did the authentic substrates ADP and ATP. In addition, formation of mono-isopentenyl ApnA and di-isopentenyl ApnA was observed. Judging by the existing biosynthetic and hydrolytic systems for ApnA in plants, ApnA and isopentenyl-ApnA may occur in the plant cells, with functional importance.

Keywords: Prenyltransferase, Cytokinin, Calorimetry, Diadenosine polyphosphates

Abbreviations: CKs, cytokinins, DMAPP, dimethylallyl diphosphate, AIPT, adenylate isopentenyltransferase, iP, isopentenyl, ITC, isothermal titration calorimetry, Ap3A, diadenosine triphosphate, Ap4A, diadenosine tetraphosphate, Ap5A, diadenosine pentaphosphate, Ap6A, diadenosine hexaphosphate, ApnA, diadenosine polyphosphates, iso-ApnA, mono-isopentenyl ApnA, di-iso-ApnA, di-isopentenyl ApnA

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PII: S0014-5793(10)00700-3

doi:10.1016/j.febslet.2010.08.038

FEBS Letters
Volume 584, Issue 18 , Pages 4083-4088, 24 September 2010

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