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

硫氧还毒素（TRX）是一种无处不在的小蛋白质，具有氧化还原活性二硫桥，负责调节广泛的靶蛋白。我们已经确定了trxz，它代表了自养生长所必需的一种新的质体TRX。拟南芥trx z T-DNA敲除突变体显示依赖于多亚基质体编码RNA聚合酶（PEP）的基因表达特异性降低。我们可以鉴定出两个果糖激酶样蛋白（FLP1和FLP2），它们是pfkb -碳水化合物激酶家族的成员，是潜在的TRX z靶蛋白。在拟南芥中，病毒诱导的FLPs基因沉默导致了类似于抑制TRX z功能的pep依赖基因转录。我们假设TRX z是叶绿体转录所必需的，可能作为氧化还原（光）的介质，并通过其靶蛋白，调节叶绿体对波动环境条件的转录活性的其他刺激。为了充分了解trxz的功能，我们计划采用转基因、分子和生化方法相结合的方法。我们认为这将导致新的氧化还原调控过程的鉴定，从而对植物氧化还原调控有了新的认识。

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.