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Summary: WHY1 enhances atpF intron splicing and influences the biogenesis of the chloroplast large ribosomal subunit. A null allele of why1 conditions albino seedlings and a weak allele conditions pale green seedlings. Both mutant classes are non-photosynthetic and seedling lethal due to the loss of chloroplast ribosomes and the reduced accumulation of all photosynthetic enzyme complexes. WHY1 binds single-stranded RNA and DNA, and is bound throughout the chloroplast nucleoid.
Image: color of mutants, and heteroalleles, depicted on a seedling leaf color scale
First reported: Prikryl et al. 2008.
Key Alleles
why1-1::MuDR, MuDR insertion is 35 bp downstream of the start codon. Ivory, seedling lethal phenotype.
why1-2::Mu, Mu1 or Mu1.7 insertion is 38 bp upstream of the start codon. Pale yellow green, seedling lethal phenotype.
Heteroallelic progeny, why1-1/why1-2, have an intermediate phenotype .
Figure 1 Mu insertion sites. Taken from Prikryl et al. Nucleic Acids Res (2008)
Map Location
Location based on sequence similarity to version 1 of the B73 reference genome sequence.
Gene Product
WHY1; required for assembly of the chloroplast large ribosomal subunit; partitions between chloroplast stroma and thylakoid membrane; binding to thylakoids is DNA-dependent; undetectable in mitochrondria. A member of the 'Whirly' protein family, comprised of two orthologous groups in angiosperms.
Figure 2. RIP-chip data showing co-immunoprecipitation of specific chloroplast RNAs with WHY1. Taken from Prikryl et al. Nucleic Acids Res. (2008)
Related Loci
atpF; the atpF intron is the major RNA ligand for WHY1. (Prikyl et al, 2008)
crs1; CRS1 protein associates with WHY1 in vivo (Prikyl et al, 2008)
References
Prikryl J, Watkins KP, Friso G, van Wijk KJ, Barkan A (2008) A member of the Whirly family is a multifunctional RNA- and DNA-binding protein that is essential for chloroplast biogenesis. Nucleic Acids Res. 36:5152-5165. PUBMED