Molecular characterization of His-Asp phosphorelay signaling factors in maize leaves: Implications of the signal divergence by cytokinin-inducible response regulators in the cytosol and the nuclei

Yasuharu Asakura, Takeshi Hagino, Yukinori Ohta, Koh Aoki, Keiko Yonekura-Sakakibara, Atsushi Deji, Tomoyuki Yamaya, Tatsuo Sugiyama, Hitoshi Sakakibara

Research output: Contribution to journalArticlepeer-review

51 Citations (Scopus)

Abstract

Genes for histidyl-aspartyl (His-Asp) phosphorelay components (His-containing phosphotransfer proteins, HP, and response regulators, RR) were isolated from Zea mays L. to characterize their function in cytokinin signaling. Six type-A RRs (ZmRR1, ZmRR2, ZmRR4-ZmRR7), 3 type-B RRs (ZmRR8-ZmRR10), and 3 HPs (ZmHP1-ZmHP3) were found in leaves. All type-A RR genes expressed in leaves were up-regulated by exogenous cytokinin. Transient expression of fusion products of the signaling modules with green fluorescent protein in epidermal leaf cells suggested cytosolic and nuclear localizations of ZmHPs, whereas type-B ZmRR8 was restricted to the nucleus. Type-A RRs were localized partly to the cytosol (ZmRR1, ZmRR2, and ZmRR3) and partly to the nucleus (ZmRR4, ZmRR5, and ZmRR6). In the yeast two-hybrid assay, ZmHP1 and ZmHP3 interacted with both cytosolic ZmRR1 and nuclear type-B ZmRRs. In vitro experiments demonstrated that ZmHPs function as a phospho-donor for ZmRRs; turnover rates of the phosphorylated state were tenfold lower in ZmRR8 and ZmRR9 than in ZmRR1 and ZmRR4. These results suggest that the His-Asp phosphorelay signaling pathway might diverge into a cytosolic and a nuclear branch in leaves of maize, and that the biochemical nature of ZmRRs is different in terms of stability of the phosphorylated status.

Original languageEnglish
Pages (from-to)331-341
Number of pages11
JournalPlant Molecular Biology
Volume52
Issue number2
DOIs
Publication statusPublished - 2003 May
Externally publishedYes

Keywords

  • Cytokinin
  • His-Asp phosphorelay
  • His-containing phosphotransfer protein
  • Response regulator
  • Two-hybrid analysis
  • Zea mays

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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