The YELLOW VARIEGATED (VAR2) locus encodes a homologue of FtsH, and ATP-dependent protease in Arabidopsis

• Published in: Plant and cell physiology 2000-12, Vol.41 (12), p.1334-1346
• Main Authors: Takechi, K. (Okayama Univ., Kurashiki (Japan). Research Inst. for Bioresources), Sodmergen, Murata, M, Motoyoshi, F, Sakamoto, W
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - genetics; Alleles; Amino Acid Sequence; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins; ARABIDOPSIS THALIANA; ATP; ATP-Dependent Proteases; Bacterial Proteins - genetics; Base Sequence; Chloroplasts - genetics; DNA Primers; FtsH protein; GENES; Genes, Plant; Genetic Linkage; Membrane Proteins - chemistry; Membrane Proteins - genetics; Microscopy, Electron; Molecular Sequence Data; MUTANTS; Phenotype; Phylogeny; Plastids - ultrastructure; PROTEASES; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Serine Endopeptidases - chemistry; Serine Endopeptidases - genetics; VAR2 gene; VARIEGATION; YELLOW VARIEGATED gene
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcd067

Variegated leaves are often caused by a nuclear recessive mutation in higher plants. Characterization of the gene responsible for variegation has shown to provide several pathways involved in plastid differentiation. Here we describe an Arabidopsis variegated mutant isolated by T-DNA tagging. The mutant displayed green and yellow sectors in all green tissues except for cotyledons. Cells in the yellow sector of the mutant contained both normal-appearing and mutant chloroplasts. The isolated mutant was shown to be an allele of the previously reported mutant, yellow variegated (var2). Cloning and molecular characterization of the VAR2 locus revealed that it potentially encodes a chloroplastic homologue of FtsH, an ATP-dependent metalloprotease that belongs to a large protein family involved in various cellular functions. ftsH-like genes appear to comprise a small gene family in Arabidopsis genome, since at least six homologues were found in addition to VAR2. Dispensability of VAR2 was therefore explained by the redundancy of genes coding for FstHs. In the yellow regions of the mutant leaves, accumulation of photosynthetic protein components in the thylakoid membrane appeared to be impaired. Based on the role of FtsH in a protein degradation pathway in plastids, we propose a possibility that VAR2 is required for plastid differentiation by avoiding partial photooxidation of developing chloroplasts.