Bisanz Cordelia, Bégot Laurent, Carol Pierre, Perez Pascual, Bligny Muriel, Pesey Hélène, Gallois Jean-Luc, Lerbs-Mache Silva, Mache Régis
Laboratoire Plastes et Differenciation cellulaire, Université Joseph Fourier et Centre National de la Recherche Scientifique (CNRS), UMR 5575, BP53, 38041 Grenoble cedex 9, France.
Plant Mol Biol. 2003 Mar;51(5):651-63. doi: 10.1023/a:1022557825768.
Altered pigmentation is an easily scored and sensitive monitor of plastid function. We analyzed in detail a yellow colored transposon-tagged mutant (dal1-2) that is allelic to the dal mutant previously identified (Babiychuk et al., 1997). Mesophyll cells of mutant plants possess abnormal nucleoids and more but smaller plastids than wild type cells. Plastid development in dal1-2 is not altered in the dark but is arrested at the early steps of thylakoid assembly. The amino acid sequence of the protein deduced from our cDNA clone is 21 amino acids longer than the previously published DAL sequence (Babiychuk et al., 1997) and allowed us to show that DAL codes for a chloroplast protein. The dal1-2 mutation has a global negative effect on plastid RNA accumulation and on expression of nuclear encoded photosynthetic genes. We show that the plastid RNA polymerases, the nuclear-encoded NEP and the plastid-encoded PEP, are functional in the mutant. Precursor 16S and 23S rRNA species specifically accumulate at a high level in the mutant but the 5'-end and the long 3'-end trailer are not modified. We suggest that the dal mutation is involved in plastid rRNA processing and consequently in translation and early chloroplast differentiation.
色素沉着改变是一种易于评分且对质体功能敏感的监测指标。我们详细分析了一个黄色的转座子标签突变体（dal1-2），它与先前鉴定的dal突变体等位（Babiychuk等人，1997年）。突变体植物的叶肉细胞具有异常的类核，并且与野生型细胞相比，质体更多但更小。dal1-2中的质体发育在黑暗中未改变，但在类囊体组装的早期步骤中停滞。从我们的cDNA克隆推导的蛋白质氨基酸序列比先前发表的DAL序列长21个氨基酸（Babiychuk等人，1997年），这使我们能够证明DAL编码一种叶绿体蛋白。dal1-2突变对质体RNA积累和核编码光合基因的表达具有全局性负面影响。我们表明，质体RNA聚合酶，即核编码的NEP和质体编码的PEP，在突变体中是有功能的。前体16S和23S rRNA物种在突变体中特异性地高水平积累，但5'端和长3'端尾未被修饰。我们认为dal突变参与质体rRNA加工，进而参与翻译和早期叶绿体分化。
