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Summary: Encodes a chloroplast PPR protein that stabilizes unspliced trnG precursor RNA by masking an endonuclease-sensitive site in the intron. PPR5 may also promote trnG group II intron splicing. The null allele of ppr5 (ppr5-1) conditions albino seedlings; a weak allele (ppr5-2) conditions pale green seedlings. Both are non-photosynthetic and seedling lethal due to the failure to accumulate mature trnG. The absence of this tRNA blocks the biogenesis of the plastid translation machinery, which in turn leads to the loss of all plastid-encoded proteins.
Images: mutant leaf color on a seedling leaf color scale
First defining reports: Beick et al. 2008; Williams-Carrier et al. 2008.
Key Alleles
ppr5-1::Mu1. Mu1 insertion is in the first exon. Ivory, seedling lethal phenotype. Mutants are smaller than wild type siblings (Beick et al. 2008).
ppr5-2::Mu1. Mu1 insertion in the 5' UTR. Slightly pale green, seedling lethal phenotype (Beick et al. 2008).
ppr5-1::Mu1/ppr5-2::Mu1 individuals are intermediate in phenotype: very pale yellow green at the base with darker green leaf tips (Beick et al. 2008).
Gene Product
PPR5 - required for chloroplast trnG maturation; specifically binds to a ~45-51 nt region of trnG precursor group II intron, covering two group II functional intron motifs (Williams-Carrier et al 2008).
Other
Null alleles of Arabidopsis PPR5 (At4g39620) are embryo lethal (Cushing et al. 2005).
References
Beick S, Schmitz-Linneweber C, Williams-Carrier R, Jensen B, Barkan A (2008) The pentatricopeptide repeat protein PPR5 stabilizes a specific tRNA precursor in maize chloroplasts. Molecular and Cellular Biology 28:5337-5347. PUBMED
Cushing DA, Forsthoefel NR, Gestaut DR, Vernon DM (2005) Arabidopsis emb175 and other ppr knockout mutants reveal essential roles for pentatricopeptide repeat (PPR) proteins in plant embryogenesis. Planta 221:424-436. PUBMED
Williams-Carrier R, Kroeger T, Barkan A (2008) Sequence-specific binding of a chloroplast pentatricopeptide repeat protein to its native group II intron ligand. RNA 14:1930-1941. PUBMED
Links: MGDB: ppr5 NCBI: ppr5 UniProt: A6YSL1