Correction of frameshift mutations in theatpBgene by translational recoding in chloroplasts ofOenotheraand tobacco

Abstract

Translational recoding, also known as ribosomal frameshifting, is a process that causes ribosome slippage along the messenger RNA, thereby changing the amino acid sequence of the synthesized protein. Whether the chloroplast employs recoding, is unknown. I-iota, a plastome mutant of Oenothera (evening primrose), carries a single adenine insertion in an oligoA stretch of atpB (encoding a β-subunit of the ATP synthase). The mutation is expected to cause synthesis of a truncated, non-functional protein. We report that a full-length AtpB protein is detectable in I-iota leaves, suggesting operation of a recoding mechanism. To characterize the phenomenon, transplastomic tobacco lines were generated, in which the atpB reading frame was altered by insertions or deletions in the oligoA motif. We found that insertion of two adenines was more efficiently compensated than insertion of a single adenine, or deletion of one or two adenines. We further show that homopolymeric composition of the oligoA stretch is essential for recoding. Plants carrying a disrupted oligoA stretch have an albino-phenotype, indicating absence of indel correction. Our work provides evidence for the operation of translational recoding in chloroplasts. Recoding enables correction of frameshift mutations and can restore photoautotrophic growth in mutants that otherwise would be lethal.

Here comes the sun: How optimization of photosynthetic light reactions can boost crop yields

“…PCC 7942, a single nucleotide polymorphism (SNP) was identified in the atpA gene, which enhanced ATP synthase contents and activity, conferring improved photosynthetic efficiency as well as carbon fixation rate, especially under stress conditions (Lou et al, 2018). Certain point mutations in the AtpB gene of the CF1 complex, on the other hand, appear to be deleterious for the assembly of the entire complex and normal plant growth, so that mutants spontaneously reverted to the wild type gene sequence (Robertson et al, 1989; Malinova et al, 2021). Additionally, a SNP of a threonine residue in the β‐subunit of CF1 (T86A in AtpB ) was identified in cold‐tolerant cucumber species when the gene sequences were compared to cold‐susceptible species.…”

Long-read sequencing characterizes mitochondrial and plastid genome variants in Arabidopsismsh1mutants

“…However, a few other pt genome variants occurred at high frequency in individual samples (Figure 7b). These individual high-frequency variants might reflect mutations in different yellow patches, which can often be often in a homoplasmic state because of random sorting early in leaf primordia (Malinova et al, 2021). Leaf variegation and albino phenotypes are common in other RRR gene mutants (for example, moc1 single mutant, why1 why3 pol1b and why1 why3 reca1 triple mutants) and transgenic plants with plastid-targeted restriction endonucleases (Zampini et al, 2015; Kobayashi et al, 2017; Sugimoto et al, 2020).…”