GUN4 protein GENOMES UNCOUPLED 4 [Arabidopsis thaliana (thale cress)] - Gene

Summary

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Gene symbol: GUN4
Gene description: protein GENOMES UNCOUPLED 4
Primary source: Araport:AT3G59400
Locus tag: AT3G59400
Gene type: protein coding
RefSeq status: REVIEWED
Organism: Arabidopsis thaliana (ecotype: Columbia)
Lineage: Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae; rosids; malvids; Brassicales; Brassicaceae; Camelineae; Arabidopsis
Also known as: GENOMES UNCOUPLED 4
Summary: GUN, genomes uncoupled, is necessary for coupling the expression of some nuclear genes to the functional state of the chloroplast. Binds to the magnesium chelatase complex and promotes formation of the substrate,a tetrapyrrole signaling molecule. Porphyrin-binding protein that enhances the activity of Mg-chelatase. Although required for chlorophyll accumulation under normal growth conditions, GUN4 is not essential for chlorophyll synthesis.
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Genomic context

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Location:: chromosome: 3

Exon count:: 1

Sequence:: Chromosome: 3; NC_003074.8 (21948501..21949796, complement)

Chromosome 3 - NC_003074.8 Genomic Context describing neighboring genes

Genomic regions, transcripts, and products

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Go to reference sequence details

Genomic Sequence:: NC_003074.8

Go to nucleotide: Graphics FASTA GenBank

Bibliography

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GeneRIFs: Gene References Into Functions

What's a GeneRIF?

GUN4 Affects the Circadian Clock and Seedlings Adaptation to Changing Light Conditions.
Title: GUN4 Affects the Circadian Clock and Seedlings Adaptation to Changing Light Conditions.
Structural basis of bilin binding by the chlorophyll biosynthesis regulator GUN4.
Title: Structural basis of bilin binding by the chlorophyll biosynthesis regulator GUN4.
In conjunction with the dark repression of 5-aminolevulinic acid synthesis, GUN4 phosphorylation minimizes the flow of intermediates into the Mg branch of the tetrapyrrole metabolic pathway for chlorophyll biosynthesis.
Title: Phosphorylation of GENOMES UNCOUPLED 4 Alters Stimulation of Mg Chelatase Activity in Angiosperms.
GUN1 and GUN4 partially restored the expression patterns of the previously detected chloroplast-associated genes, thereby ameliorating the slow-greening phenotype of sg1.
Title: The tetratricopeptide repeat-containing protein slow green1 is required for chloroplast development in Arabidopsis.
ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes.
Title: GUN4-porphyrin complexes bind the ChlH/GUN5 subunit of Mg-Chelatase and promote chlorophyll biosynthesis in Arabidopsis.
Data show that mutant subunits act as inhibitors of ChlH, and this inhibition is reversed upon addition of Gun4.
Title: Abolition of magnesium chelatase activity by the gun5 mutation and reversal by Gun4.
GUN4 stimulates chlorophyll biosynthesis not only by activating Mg-chelatase but also by promoting interactions between ChlH and chloroplast membranes
Title: Porphyrins promote the association of GENOMES UNCOUPLED 4 and a Mg-chelatase subunit with chloroplast membranes.
The physical-chemical basis for understanding GUN4 biological activity, including its role in the stimulation of Mg-chelatase activity.
Title: Structure of the Mg-chelatase cofactor GUN4 reveals a novel hand-shaped fold for porphyrin binding.

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Interactions

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Products	Interactant	Other Gene	Complex	Source	Pubs	Description

General gene information

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NM_115802.4

Supported by ESTs:

Gene Ontology Provided by TAIR

Function	Evidence Code	Pubs
enables enzyme activator activity	TAS Traceable Author Statement more info	PubMed
enables enzyme binding	IPI Inferred from Physical Interaction more info	PubMed
enables tetrapyrrole binding	IDA Inferred from Direct Assay more info	PubMed

Process	Evidence Code	Pubs
acts_upstream_of_or_within chlorophyll biosynthetic process	TAS Traceable Author Statement more info	PubMed
acts_upstream_of_or_within chloroplast-nucleus signaling pathway	IMP Inferred from Mutant Phenotype more info	PubMed

Component	Evidence Code	Pubs
located_in chloroplast	HDA more info	PubMed
located_in chloroplast	IDA Inferred from Direct Assay more info	PubMed
located_in chloroplast	ISM Inferred from Sequence Model more info

General protein information

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Preferred Names: protein GENOMES UNCOUPLED 4

NP_191499.1

GENOMES UNCOUPLED 4 (GUN4); FUNCTIONS IN: tetrapyrrole binding, enzyme binding; INVOLVED IN: chlorophyll biosynthetic process, chloroplast-nucleus signaling pathway, positive regulation of catalytic activity; LOCATED IN: chloroplast; EXPRESSED IN: 20 plant structures; EXPRESSED DURING: 13 growth stages; CONTAINS InterPro DOMAIN/s: GUN4-like (InterPro:IPR008629); Has 685 Blast hits to 680 proteins in 101 species: Archae - 0; Bacteria - 474; Metazoa - 4; Fungi - 2; Plants - 53; Viruses - 0; Other Eukaryotes - 152 (source: NCBI BLink).