BUNDLE SHEATH DEFECTIVE2, a novel protein required for post-translational regulation of the rbcL gene of maize
BUNDLE SHEATH DEFECTIVE2, a novel protein required for post-translational regulation of the rbcL gene of maize
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DOI：
10.1105/tpc.11.5.849
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发表时间：
1999-05-01
期刊：
影响因子：
11.6
通讯作者：
Langdale, JA
中科院分区：
文献类型：
--
作者：
Brutnell, TP;Sawers, RJH;Langdale, JA
Bsd 2基因是玉米核酮糖-1，5-二磷酸羧化酶/加氧酶（Rubisco）积累所必需的基因。以Mutator转座元件为探针，我们发现了一个与Bsd 2基因共分离的紧密连锁的限制性片段长度多态性。使用全长cDNA克隆分离在这个屏幕上，我们表明，丰富的0.6 kb的转录本可以检测到野生型植物，但不是在bsd 2-m1植物。这种0.6 kb的转录本在携带来自bsd 2-m1的等位基因的植物中积累到低水平，该等位基因可导致不太严重的突变表型。综上所述，这些数据有力地表明我们已经克隆了Bsd 2基因。全长cDNA克隆的序列分析揭示了一个叶绿体靶向序列和BSD 2和DnaJ类分子伴侣之间共享的同源性区域。该区域的同源性仅限于DnaJ中富含半胱氨酸的Zn结合结构域，据信其在蛋白质-蛋白质相互作用中发挥作用。我们表明，BSD 2是针对叶绿体，但不参与一般的光合复合物组装或蛋白质进口。在bsd 2突变体中，我们不能检测到Rubisco蛋白，但叶绿体编码的Rubisco大亚基转录本（rbcL）是丰富的，并与多核糖体在维管束鞘和叶肉细胞。通过表征Bsd 2的表达模式和分析bsd 2赋予的表型，我们提出了一个模型，BSD 2在玉米rbcL的翻译后调控。
The Bundle sheath defective2 (Bsd2) gene is required for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) accumulation in maize, Using a Mutator transposable element as a molecular probe, we identified a tightly linked restriction fragment length polymorphism that cosegregated with the bsd2-conferred phenotype, This fragment was cloned, and sequences flanking the Mutator insertion were used to screen a maize leaf cDNA library. Using a full-length cDNA clone isolated in this screen, we show that an abundant 0.6-kb transcript could be detected in wild-type plants but not in bsd2-m1 plants. This 0.6-kb transcript accumulated to low levels in plants carrying an allele derived from bsd2-m1 that conditions a less severe mutant phenotype. Taken together, these data strongly suggest that we have cloned the Bsd2 gene. Sequence analysis of the full-length cDNA clone revealed a chloroplast targeting sequence and a region of homology shared between BSD2 and the DnaJ class of molecular chaperones. This region of homology is limited to a cysteine-rich Zn binding domain in DnaJ believed to play a role in protein-protein interactions. We show that BSD2 is targeted to the chloroplast but is not involved in general photosynthetic complex assembly or protein import. In bsd2 mutants, we could not detect the Rubisco protein, but the chloroplast-encoded Rubisco large subunit transcript (rbcL) was abundant and associated with polysomes in both bundle sheath and mesophyll cells. By characterizing Bsd2 expression patterns and analyzing the bsd2-conferred phenotype, we propose a model for BSD2 in the post-translational regulation of rbcL in maize.