A Peptide Chain Release Factor 2 Affects the Stability of UGA-Containing Transcripts in Arabidopsis Chloroplasts

Abstract

Positional cloning of the hcf109 ( high chlorophyll fluorescence ) mutation in Arabidopsis has identified a nucleus-encoded, plastid-localized release factor 2-like protein, AtprfB, indicating that the processes of translational termination in chloroplasts resemble those of eubacteria. Control of atprfB expression by light and tissues is connected to chloroplast development. A point mutation at the last nucleotide of the second intron causes a new splice site farther downstream, resulting in a deletion of seven amino acid residues in the N-terminal region of the Hcf109 protein. The mutation causes decreased stability of UGA-containing mRNAs. Our data suggest that transcripts with UGA stop codons are terminated exclusively by AtprfB in chloroplasts and that AtprfB is involved in the regulation of both mRNA stability and protein synthesis. Furthermore, sequence data reveal a ؉ 1 frameshift at an internal in-frame TGA stop codon in the progenitor prfB gene of cyanobacteria. The expression pattern and functions of atprfB could reflect evolutionary driving forces toward the conservation of TGA stop codons exclusively in plastid genomes of land plants.

Inactivation of the Chloroplast ATP Synthase γ Subunit Results in High Non-photochemical Fluorescence Quenching and Altered Nuclear Gene Expression in Arabidopsis thaliana

“…Substantial quenching below the initial F o fluorescence level during illumination was also observed in several other Arabidopsis mutants such as hcf109 (32,39) and in a tobacco psbF point mutation (69). This quenching also relaxes after switching off actinic light and reaches the F o level with similar kinetics to those found in dpa1.…”

“…The appearing signals in the gels could be assigned to individual subunits of the thylakoid membrane, i.e. PsaA/B, AtpA/B, PsbB/C, and PsbA/D, due to their abundance and known electrophoretic mobilities and by mutant analysis (32). The protein labeling patterns in the mutant and wild type were identical with respect to the size and the numbers of all detectable polypeptides and their intensity of labeling.…”

“…The signals were analyzed on autoradiographs using Fuji Bio Imaging plates type BASIII, a Fuji Bio Imaging analyzer, and the Aida software package (Raytest, Sprockhövel/Germany). Probes for atpH/I, atpF, atpA, and atpC1 used for Northern analysis were as described (32). To confirm the array expression data, probes for petC, psbS, lhcB6, and psaD1 genes were used in Northern analysis.…”

PsbN Is Required for Assembly of the Photosystem II Reaction Center in Nicotiana tabacum

“…RNA isolation and gel blot analysis was performed as described (Meurer et al, 2002) using end labeling of strand-specific 80mer oligonucleotides with T4 polynucleotide kinase (New England Biolabs).…”

HIGH CHLOROPHYLL FLUORESCENCE145 Binds to and Stabilizes the psaA 5′ UTR via a Newly Defined Repeat Motif in Embryophyta

“…Homologs of only few factors for chloroplast RNA metabolism are also found in cyanobacteria. However, they significantly diversified by recruiting novel domains and/or extensions and changed their functions, as was found for CHLOROPLAST RNA SPLICING2 (Jenkins and Barkan, 2001), HCF109 (Meurer et al, 2002), CHLOROPLAST RNA SPLICING AND RIBOSOME MATURATION (Barkan et al, 2007), PrfB3 (Stoppel et al, 2011), and RNase E (Mudd et al, 2008;Schein et al, 2008;.…”