LPA66 Is Required for EditingpsbFChloroplast Transcripts in Arabidopsis

Wenhe Cai,Meijuan Zou,Jinkui Guo,Lixin Zhang,Lianwei Peng,Jinfang Ma,Daili Ji,Congming Lu

doi:10.1104/pp.109.136812

Abstract

To gain insight into the molecular mechanism of RNA editing, we have characterized the low psii accumulation66 (lpa66) Arabidopsis (Arabidopsis thaliana) mutant, which displays a high chlorophyll fluorescence phenotype. Its perturbed chlorophyll fluorescence is reflected in reduced levels of photosystem II (PSII) proteins. In vivo protein labeling showed that synthesis rates of the PSII reaction center protein D1/D2 were lower, and turnover rates of PSII core proteins higher, than in wild-type counterparts. The assembly of newly synthesized proteins into PSII occurs in the lpa66 mutant but with reduced efficiency compared with the wild type. LPA66 encodes a chloroplast protein of the pentatricopeptide repeat family. In lpa66 mutants, editing of psbF that converts serine to phenylalanine is specifically impaired. Thus, LPA66 is specifically required for editing the psbF transcripts in Arabidopsis, and the amino acid alternation due to lack of editing strongly affects the efficiency of the assembly of PSII complexes.

Highlights

To gain insight into the molecular mechanism of RNA editing, we have characterized the low psii accumulation66 Arabidopsis (Arabidopsis thaliana) mutant, which displays a high chlorophyll fluorescence phenotype
Genetic analysis showed that the lpa66-1 mutation was recessive and that the lpa66-1 mutant phenotype did not cosegregate with the phosphinothricin resistance marker, indicating that the mutated LPA66 gene is not tagged by the T-DNA
Mapbased cloning of the lpa66-1 mutant based on simple sequence length polymorphism molecular markers revealed a nucleotide substitution in the gene At5g48910 (Fig. 2A), which led to an amino acid change of Gly to Arg (Fig. 2B)

Summary

Introduction

To gain insight into the molecular mechanism of RNA editing, we have characterized the low psii accumulation (lpa66) Arabidopsis (Arabidopsis thaliana) mutant, which displays a high chlorophyll fluorescence phenotype. LPA66 is required for editing the psbF transcripts in Arabidopsis, and the amino acid alternation due to lack of editing strongly affects the efficiency of the assembly of PSII complexes. The plant PPR protein family can be divided into two subfamilies on the basis of their motif content and organization, the P subfamily and combinatorial and modular proteins (PCMP) subfamilies (Lurin et al, 2004; Rivals et al, 2006). Members of the PCMP subfamily ( referred to as the PLS subfamily) contain PPR-like motifs with either short (PPR-like S) or longer (PPR-like L) repeats This subfamily is specific to land plants and is subdivided into three subgroups according to their C-terminal contents: PLS, E, and DYW proteins (Lurin et al, 2004; Rivals et al, 2006). The other five members belong to the DYW subgroup, which contains the DYW domain besides the E domain

Methods

Results

Conclusion