A cell plate specific callose synthase and its interaction with phragmoplastin
A cell plate specific callose synthase and its interaction with phragmoplastin
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DOI：
10.1105/tpc.13.4.755
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发表时间：
2001-04-01
期刊：
影响因子：
11.6
通讯作者：
Verma, DPS
中科院分区：
文献类型：
--
作者：
Hong, ZL;Delauney, AJ;Verma, DPS
胼胝质在植物的形成细胞板和其他几个位置合成。我们克隆了一个拟南芥cDNA编码胼胝质合成酶（CalS 1）催化亚基。CalS 1基因由42个外显子和41个内含子组成，转录成6.0 kb的mRNA。推导出的肽，具有大约226 kD的分子量，显示与酵母1，3-β-葡聚糖糖苷酶的序列同源性，并不同于植物纤维素糖苷酶。CalS 1包含16个预测的跨膜螺旋，N-末端区域和一个面向细胞质的大的中央环。CalS 1与两种细胞板相关蛋白质相互作用，即成膜蛋白和与CalS复合物共纯化的新型UDP-葡萄糖转移酶。CalS 1是一种细胞板特异性酶，这一点通过以下观察得到证实：绿色荧光蛋白-CalS 1融合蛋白定位于生长的细胞板，CalS 1在转基因烟草细胞中的表达增强了形成细胞板上的胼胝质合成，并且这些细胞系表现出更高水平的CalS活性。这些数据还表明，植物CalS可能与UDP-葡萄糖转移酶形成复合物，以促进胼胝质合成底物的转移。
Callose is synthesized on the forming cell plate and several other locations in the plant. We cloned an Arabidopsis cDNA encoding a callose synthase (CalS1) catalytic subunit. The CalS1 gene comprises 42 exons with 41 introns and is transcribed into a 6.0-kb mRNA. The deduced peptide, with an approximate molecular mass of 226 kD, showed sequence homology with the yeast 1,3-beta -glucan synthases and is distinct from plant cellulose synthases. CalS1 contains 16 predicted transmembrane helices with the N-terminal region and a large central loop facing the cytoplasm. CalS1 interacts with two cell plate-associated proteins, phragmoplastin and a novel UDP-glucose transferase that copurifies with the CalS complex. That CalS1 is a cell plate-specific enzyme is demonstrated by the observations that the green fluorescent protein-CalS1 fusion protein was localized at the growing cell plate, that expression of CalS1 in transgenic tobacco cells enhanced callose synthesis on the forming cell plate, and that these cell lines exhibited higher levels of CalS activity. These data also suggest that plant CalS may form a complex with UDP-glucose transferase to facilitate the transfer of substrate for callose synthesis.