Transcription factor phosphorylation by a protein kinase associated with chloroplast RNA polymerase from mustard (Sinapis alba)
Transcription factor phosphorylation by a protein kinase associated with chloroplast RNA polymerase from mustard (Sinapis alba)
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DOI：
10.1023/a:1005802909902
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发表时间：
1997-05-01
影响因子：
5.1
通讯作者：
Link, G
中科院分区：
文献类型：
--
作者：
Baginsky, S;Tiller, K;Link, G
叶绿体转录机制涉及多种成分，既有催化功能，又有调节功能。在这里，我们描述了一种丝氨酸特异的蛋白激酶活性，它与主要的叶绿体RNA聚合酶相关，并在体外磷酸化Sigma样转录因子。部分纯化的RNA聚合酶(KPC，KK聚合酶复合体)是一种54 kDa的多肽。这种多肽也存在于一个较小的复合体中，该复合体包含几个假定的聚合酶亚基，并显示出激酶活性，但缺乏转录活性(KC，激酶复合体)。尽管54 kDa组分不能在不失去活性的情况下与该复合体的其余部分进行层析分离，但它在电泳印迹分析中保留了剩余的激酶活性。聚合酶相关的激酶本身受到体外磷酸化和去磷酸化的影响，这增加了它是通过因子磷酸化控制体内叶绿体转录的信号级联反应的可能性。
The chloroplast transcription machinery involves multiple components with both catalytic and regulatory functions. Here we describe a serine-specific protein kinase activity that is associated with the major chloroplast RNA polymerase and phosphorylates sigma-like transcription factors in vitro. The kinase activity can be assigned to a 54 kDa polypeptide of partially purified RNA polymerase (KPC, kinase polymerase complex). This polypeptide is also present in a smaller complex that contains several putative polymerase subunits and reveals kinase activity but lacks transcription activity (KC, kinase complex). Although the 54 kDa component could not be chromatographically separated from the rest of this complex without loss of activity, it retained residual kinase activity in an electrophoretic blot assay. The polymerase-associated kinase is itself affected by in vitro phosphorylation and dephosphorylation, which raises the possibility that it is part of a signalling cascade that controls chloroplast transcription in vivo by factor phosphorylation.