Planta

, Volume 200, Issue 1, pp 2–12

Cytokinin controls the cell cycle at mitosis by stimulating the tyrosine dephosphorylation and activation of p34cdc2-like H1 histone kinase

  • Kerong Zhang
  • David S. Letham
  • Peter C. L. John
Article

DOI: 10.1007/BF00196642

Cite this article as:
Zhang, K., Letham, D.S. & John, P.C.L. Planta (1996) 200: 2. doi:10.1007/BF00196642

Abstract

In excised pith parenchyma from Nicotiana tabacum L. cv. Wisconsin Havana 38, auxin (naphthalene-1-acetic acid) together with cytokinin (6-benzylaminopurine) induced a greater than 40-fold increase in a p34cdc2-like protein, recoverable in the p13suc1-binding fraction, that had high H1 histone kinase activity, but enzyme induced without cytokinin was inactive. In suspension-cultured N. plumbaginifolia Viv., cytokinin (kinetin) was stringently required only in late G2 phase of the cell division cycle (cdc) and cells lacking kinetin arrested in G2 phase with inactive p34cdc2-like H1 histone kinase. Control of the Cdc2 kinase by inhibitory tyrosine phosphorylation was indicated by high phosphotyrosine in the inactive enzyme of arrested pith and suspension cells. Yeast cdc25 phosphatase, which is specific for removal of phosphate from tyrosine at the active site of p34cdc2 enzyme, was expressed in bacteria and caused extensive in-vitro activation of p13suc1-purified enzyme from pith and suspension cells cultured without cytokinin. Cytokinin stimulated the removal of phosphate, activation of the enzyme and rapid synchronous entry into mitosis. Therefore, plants can control cell division by tyrosine phosphorylation of Cdc2 but differ from somatic animal cells in coupling this mitotic control to hormonal signals.

Key words

Cell division proteins (cdc2, cdc25, cdk) Nicotiana (p34cdc2-like protein) Phosphotyrosine 

Abbreviations

BAP

6-benzylaminopurine

BrdUrd

5-bromo-2-deoxyuridine

cdc

cell division cycle

Cdc25

cdc phospho-protein phosphatase

CKI

cyclin dependent kinase inhibitor

2,4-D

2,4-dichlorophenoxyacetic acid

DAPI

4′,6′ diamidino-2-phenylindole

GST-cdc25

glutathione sulfur transferase-truncated cdc25 fusion

MS

Murashige and Skoog (1962)

NAA

naphthalene-1-acetic acid

p34cdc2

34-kDa product of the cdc2 gene

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • Kerong Zhang
    • 1
  • David S. Letham
    • 1
    • 2
  • Peter C. L. John
    • 1
    • 2
  1. 1.Plant Cell Biology Group, Research School of Biological SciencesThe Australian National UniversityAustralia
  2. 2.Cooperative Research Centre for Plant ScienceCanberraAustralia

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