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 ( g enomes un coupled) 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.
Keywords
PlastidBiologyMutantChloroplastNuclear geneArabidopsisArabidopsis thalianaProtein subunitCell biologyGeneRetrograde signalingGeneticsNuclear localization sequenceSignal transductionGenome
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Publication Info
- Year
- 2001
- Type
- article
- Volume
- 98
- Issue
- 4
- Pages
- 2053-2058
- Citations
- 643
- Access
- Closed
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Cite This
Nobuyoshi Mochizuki,
Judy A. Brusslan,
Robert M. Larkin
et al.
(2001).
<i>Arabidopsis genomes uncoupled 5</i> ( <i>GUN5</i> ) mutant reveals the involvement of Mg-chelatase H subunit in plastid-to-nucleus signal transduction.
Proceedings of the National Academy of Sciences
, 98
(4)
, 2053-2058.
https://doi.org/10.1073/pnas.98.4.2053
Identifiers
- DOI
- 10.1073/pnas.98.4.2053