An Arabidopsis homolog of the bacterial peptidoglycan synthesis enzyme MurE has an essential role in chloroplast development
An Arabidopsis homolog of the bacterial peptidoglycan synthesis enzyme MurE has an essential role in chloroplast development
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DOI：
10.1111/j.1365-313x.2007.03379.x
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发表时间：
2008-03-01
期刊：
影响因子：
7.2
通讯作者：
Takano, Hiroyoshi
中科院分区：
文献类型：
--
作者：
Garcia, Marlon;Myouga, Fumiyoshi;Takano, Hiroyoshi
细菌MurE基因编码的酶在细菌肽聚糖生物合成中催化尿苷二磷酸-N-乙酰胞壁酸-三肽的ATP依赖性形成。拟南芥基因组含有一个与细菌MurE同源的基因：AtMurE。在正常条件下，AtMurE在叶和花中表达，但不在根或茎中表达。基于序列的预测和分析的GFP融合的N末端的AtMurE，以及全长蛋白质，表明AtMurE定位到质体。我们在A. thaliana.所有4个等位基因均表现为白色表型，A.拟南芥AtMurE反义株系表现为淡绿色表型。这些结果表明，AtMurE参与叶绿体生物发生。突变体细胞的类囊体膜发育受到抑制。对突变株系的RT-PCR分析表明，依赖于多亚基质体编码的RNA聚合酶的基因的表达降低。为了分析蓝细菌、藓类植物小立碗藓和高等植物的MurE基因之间的功能关系，用每个细胞显示少量大叶绿体的小立碗藓（Pp）MurE敲除系进行互补测定。虽然与PpMurE的N-末端区域融合的鱼腥藻MurE补充了展叶藻中的大叶绿体表型，但用AtMurE转化不能补充该表型。这些结果表明AtMurE在功能上不同于细菌和苔藓MurE蛋白。
Enzymes encoded by bacterial MurE genes catalyze the ATP-dependent formation of uridine diphosphate-N-acetylmuramic acid-tripeptide in bacterial peptidoglycan biosynthesis. The Arabidopsis thaliana genome contains one gene with homology to the bacterial MurE:AtMurE. Under normal conditions AtMurE is expressed in leaves and flowers, but not in roots or stems. Sequence-based predictions and analyses of GFP fusions of the N terminus of AtMurE, as well as the full-length protein, suggest that AtMurE localizes to plastids. We identified three T-DNA-tagged and one Ds-tagged mutant alleles of AtMurE in A. thaliana. All four alleles show a white phenotype, and A. thaliana antisense AtMurE lines showed a pale-green phenotype. These results suggest that AtMurE is involved in chloroplast biogenesis. Cells of the mutants were inhibited in thylakoid membrane development. RT-PCR analysis of the mutant lines suggested that the expression of genes that depend on a multisubunit plastid-encoded RNA polymerase was decreased. To analyze the functional relationships between the MurE genes of cyanobacteria, the moss Physcomitrella patens and higher plants, a complementation assay was carried out with a P. patens (Pp) MurE knock-out line, which exhibits a small number of macrochloroplasts per cell. Although the Anabaena MurE, fused with the N-terminal region of PpMurE, complemented the macrochloroplast phenotype in P. patens, transformation with AtMurE did not complement this phenotype. These results suggest that AtMurE is functionally divergent from the bacterial and moss MurE proteins.