Regulation of chloroplast gene expression by the maturase MatK

内含子成熟酶MatK是叶绿体基因组中编码的唯一假定的RNA剪接因子。与相关的单特异性细菌成熟酶不同，MatK能够与多个内含子结合。虽然所有其他叶绿体RNA加工因子都是核编码的，但MatK一直保持在所有自养的含内含子的第II组链霉菌的叶绿体基因组中。由于细菌成熟酶已被证明可以调节其自身的表达，因此在此假设MatK也参与调节反馈环，该调节反馈环需要其在叶绿体中顺式表达并阻止基因转移到细胞核。为了验证这一假设，我们提出了一个三管齐下的方法：（1）我们将尝试通过transplastomic方法干扰MatK与其自身RNA的相互作用。(2)为了拥抱更大的MatK网络，我们将测量已知与MatK相互作用或依赖于MatK在烟草发育中的功能的各种组分的动力学。这将允许开发基因表达的MatK依赖性调节的数学模型，以识别网络中的关键步骤/因子。(3)为了了解MatK的生物化学网络，我们将通过质谱和其他生物化学技术来表征含有MatK的核糖核蛋白颗粒。

The intron maturase MatK is the only putative RNA splicing factor encoded in the chloroplast genome. Different from related monospecific bacterial maturases, MatK is capable of associating with multiple introns. While all other chloroplast RNA processing factors are nuclear encoded, MatK has been maintained in the chloroplast genome in all autotrophic, group II intron-containing streptophytes. Because of the fact that bacterial maturases have been demonstrated to regulate their own expression, it is here hypothesized that MatK is also involved in regulatory feed-back loops that require its expression in cis in the chloroplast and prevent transfer of the gene to the nucleus. To test this hypothesis, a three-pronged approach is proposed: (1) We will try to perturb the interaction of MatK with its own RNA by transplastomic approaches. (2) To embrace the larger MatK-network we will measure kinetics of various components known to interact with MatK or to be dependent on MatK function across tobacco development. This will allow developing a mathematical model of MatK-dependent regulation of gene expression in order to identify critical steps/factors in the network. (3) In order to understand also the biochemical network of MatK, we will characterize MatK-containing ribonucleoprotein particles by mass-spectrometry and additional biochemical techniques.