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Arabidopsis genomes uncoupled 5 (GUN5) mutant reveals the involvement of Mg-chelatase H subunit in plastid-to-nucleus signal transduction

Academic Article
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Overview

authors

  • Mochizuki, N.
  • Brusslan, J. A.
  • Larkin, R.
  • Nagatani, A.

publication date

  • 2001

journal

  • Proceedings of the National Academy of Sciences of the United States of America  Journal

abstract

  • A plastid-derived signal plays an important role in the coordinated expression of both nuclear- and chloroplast-localized genes that encode photosynthesis-related proteins. Arabidopsis GUN (genomes uncoupled) loci have been identified as components of plastid-to-nucleus signal transduction. Unlike wild-type plants, gun mutants have nuclear Lhcb1 expression in the absence of chloroplast development. We observed a synergistic phenotype in some gun double-mutant combinations, suggesting there are at least two independent pathways in plastid-to-nucleus signal transduction. There is a reduction of chlorophyll accumulation in gun4 and gun5 mutant plants, and a gun4gun5 double mutant shows an albino phenotype. We cloned the GUN5 gene, which encodes the ChlH subunit of Mg-chelatase. We also show that gun2 and gun3 are alleles of the known photomorphogenic mutants, hy1 and hy2, which are required for phytochromobilin synthesis from heme. These findings suggest that certain perturbations of the tetrapyrrole biosynthetic pathway generate a signal from chloroplasts that causes transcriptional repression of nuclear genes encoding plastid-localized proteins. The comparison of mutant phenotypes of gun5 and another Mg-chelatase subunit (ChlI) mutant suggests a specific function for ChlH protein in the plastid-signaling pathway.

subject areas

  • Amino Acid Sequence
  • Arabidopsis
  • Cell Nucleus
  • Cloning, Molecular
  • Genome, Plant
  • Lyases
  • Magnesium
  • Molecular Sequence Data
  • Mutagenesis
  • Plant Proteins
  • Plastids
  • Signal Transduction
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Identity

PubMed Central ID

  • PMC29380

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.98.4.2053

PubMed ID

  • 11172074
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Additional Document Info

start page

  • 2053

end page

  • 2058

volume

  • 98

issue

  • 4

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