The auxin-induced maize gene ZmSAUR2 encodes a short-lived nuclear protein expressed in elongating tissues
The auxin-induced maize gene ZmSAUR2 encodes a short-lived nuclear protein expressed in elongating tissues
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DOI：
10.1074/jbc.m212585200
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发表时间：
2003-06-27
影响因子：
4.8
通讯作者：
Lehle, L
中科院分区：
文献类型：
--
作者：
Knauss, S;Rohrmeier, T;Lehle, L
通过对生长素诱导的玉米胚芽鞘cDNA文库的差异筛选，我们分离并鉴定了一个SAUR基因，命名为ZmSAUR 2，属于SAUR家族的一个尚未鉴定的亚型。ZmSAUR 2编码一个15.3-kDa的蛋白质，并且在伸长的胚芽鞘组织中特异性地被生长素诱导，但在初生叶或根中不被诱导。转录水平迅速增加，在几分钟内和之前生长素刺激的胚芽鞘段伸长。放线菌酮也诱导ZmSAUR 2转录，如已显示的其他早期生长素诱导的基因，而脱落酸，油菜素，乙烯，赤霉酸，激动素，茉莉酸甲酯没有引起ZmSAUR 2 mRNA丰度的增加。在使用生长素诱导的胚芽鞘和抗ZmSAUR 2抗体的脉冲追踪实验中，我们能够沉淀预期分子量的蛋白质，并确定约7分钟的半衰期，这是真核生物中已知的最短的半衰期之一。在凝胶迁移试验中，证明了钙调素与ZmSAUR 2的结合，表明了转录后调节的可能性。在用ZmSAUR 2：：GUS构建体转化洋葱表皮细胞后，在细胞核中检测到相应的嵌合蛋白。结果表明，ZmSAUR 2编码一个短寿命的核蛋白，可能参与生长素介导的细胞伸长。
By differential screening of a cDNA library from auxin-induced maize coleoptiles we have isolated and characterized a SAUR gene, designated ZmSAUR2, belonging to a not yet characterized subtype of the SAUR family. ZmSAUR2 encodes a 15.3-kDa protein and is specifically induced by auxin in elongating coleoptile tissue but not in primary leaves or in roots. The transcript level rapidly increased within minutes and preceded auxin-stimulated elongation of coleoptile segments. Cycloheximide also induced ZmSAUR2 transcription, as has been shown for other early auxin-induced genes, whereas abscisic acid, brassinolide, ethylene, gibberellic acid, kinetin, and methyl jasmonate did not provoke an increase in ZmSAUR2 mRNA abundance. In pulse-chase experiments using auxin-induced coleoptiles and an anti-ZmSAUR2 antibody we were able to precipitate a protein of the expected molecular mass and to determine a half-life of about 7 min, which is among the shortest known in eukaryotes. In gel shift assays binding of calmodulin to ZmSAUR2 was demonstrated, suggesting the possibility of post-transcriptional regulation. Upon transformation of onion epidermal cells with a ZmSAUR2::GUS construct the corresponding chimeric protein was detected in the nucleus. The results suggest that ZmSAUR2 encodes a short-lived nuclear protein that might be involved in auxin-mediated cell elongation.