RRC ID 12329
著者 Hirabayashi Y, Kikuchi S, Oishi M, Nakai M.
タイトル In vivo studies on the roles of two closely related Arabidopsis Tic20 proteins, AtTic20-I and AtTic20-IV.
ジャーナル Plant Cell Physiol
Abstract Protein translocation across the inner envelope of plastids is mediated by the TIC (translocon at the inner envelope membrane of chloroplasts) protein translocation machinery. Tic20 has been shown to function as a central component of TIC machinery. The Arabidopsis genome encodes four Tic20 homologous proteins, AtTic20-I, AtTic20-II, AtTIC20-IV and AtTic20-V, among which only AtTic20-I has been extensively characterized and demonstrated to be essential for protein import into chloroplasts. AtTic20-I is more closely related to AtTic20-IV than to AtTic20-II or AtTic20-V, whereas AtTic20-II and AtTic20-V show higher similarities to each other than to AtTic20-I or AtTic20-IV. Here, we show that AtTic20-IV is expressed mainly in roots whereas AtTic20-I is more abundant in shoots than in roots. Although AtTic20-IV is dispensable for viability in the wild-type background, interestingly, expression of AtTic20-IV is markedly elevated in both shoots and roots in the tic20-I knockout mutant that exhibits severe albino and seedling-lethal phenotypes. The albino tic20-I seedlings do not accumulate any of the photosynthetic proteins analyzed, but the plastids can still import non-photosynthetic housekeeping proteins. This residual import ability of the tic20-I mutant can be attributed to partial compensation by the elevated expression of AtTic20-IV, since a double knockout mutant of AtTic20-I and AtTic20-IV exhibits more severe embryonic lethality. Further overexpression of AtTic20-IV in the tic20-I mutant can only marginally rescue the accumulation of photosynthetic proteins in the albino seedlings. These data demonstrate an absolute requirement of at least one of the two closely related Tic20 proteins in protein translocation across the inner envelope of plastids and also suggest their distinct substrate preferences.
巻・号 52(3)
ページ 469-78
公開日 2011-3-1
DOI 10.1093/pcp/pcr010
PII pcr010
PMID 21266460
MeSH Amino Acid Sequence Arabidopsis / embryology Arabidopsis / genetics Arabidopsis / metabolism* Arabidopsis Proteins / chemistry Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Crosses, Genetic Gene Expression Profiling Gene Expression Regulation, Plant Gene Knockout Techniques Membrane Proteins / chemistry Membrane Proteins / genetics Membrane Proteins / metabolism* Membrane Transport Proteins / chemistry Membrane Transport Proteins / genetics Membrane Transport Proteins / metabolism* Models, Biological Molecular Sequence Data Mutation / genetics Phenotype Plant Roots / genetics Plant Shoots / genetics Plants, Genetically Modified Seeds / genetics Sequence Analysis, Protein
IF 4.062
引用数 24
WOS 分野 PLANT SCIENCES CELL BIOLOGY
リソース情報
シロイヌナズナ / 植物培養細胞・遺伝子 pda01661