Functional characterization of a novel plastidal thioredoxin and its putative target proteins

硫氧还蛋白（TRX）是一种具有氧化还原活性的二硫键的小而普遍存在的蛋白质，负责调节广泛的靶蛋白。我们已经确定了TRX Z，代表一种新的质体TRX必需的自养生长。拟南芥trx z T-DNA敲除突变体显示依赖于多亚基质体编码的RNA聚合酶（PEP）的基因表达的特异性降低。我们可以确定两个果糖激酶样蛋白（FLP 1和FLP 2），pfkB-碳水化合物激酶家族的成员，作为潜在的TRX z靶蛋白。病毒诱导的N. benthamiana导致PEP依赖性基因转录的抑制与拟南芥中TRX z功能的抑制相似。我们假设，TRX Z是叶绿体转录所需的可能作为一个介体的氧化还原-（光），并通过其靶蛋白，其他刺激调节转录活性的叶绿体在波动的环境条件。为了充分了解TRX z的功能，我们计划使用转基因、分子和生物化学方法的组合。我们建议，这将导致识别新的氧化还原调节过程，从而在植物中氧化还原调节的新见解。

Thioredoxins (TRX) are small ubiquitous proteins with a redox-active disulfide bridge responsible for the regulation of a broad range of target proteins. We have identified TRX z that represents a novel plastidial TRX essential for autotrophic growth. The Arabidopsis trx z T-DNA knockout mutant displays a specific decrease in the expression of genes that depend on a multi-subunit plastid-encoded RNA polymerase (PEP). We could identify two fructokinase-like proteins (FLP1 and FLP2), members of the pfkB-carbohydrate kinase family, as potential TRX z target proteins. Virus-induced gene silencing of FLPs in N. benthamiana led to a similar repression of PEP-dependent gene transcription as the suppression of TRX z function in Arabidopsis. We hypothesize that TRX z is required for chloroplast transcription possibly serving as a mediator of redox-(light-) and, via its target proteins, other stimuli regulating transcriptional activity in chloroplasts in response to fluctuating environmental conditions. To fully understand the function of TRX z we are planning to use a combination of transgenic, molecular and biochemical approaches. We propose that this will lead to the identification of novel redox regulated processes and thus new insights into redox regulation in plants.