Arabidopsis PDE191Encodes An MtERF Family Member Required For Transcription Termination Of RpoA Gene

The mitochondrial transcription termination factors (mTERF), a multifunctionprotein family, containing four subfamilies named mTERF1-4, are mainly confirmedcrucial for mitochondrial gene replication, transcription initiation and termination inanimals. In this paper, we obtained an Arabidopsis albino mutant, named pde191-1,due to a T-DNA insertion in PDE191gene, whose submicroscopic structure ofchloroplast was abnormal. PDE191contains732-33amino acids long mTERF motifrepeats. Subcellular localization indicated PDE191was targeted to chloroplasts.PDE191was studied on transcription termination in chloroplast by Real Time RT-PCRand we found PDE191defection cause unable to terminate transcription normally ofa series of chloroplast genes, especially rpoA. The expression level of the intervalsequence between rpoA and its downstream gene in pde191-1mutant is20timesthe same as that in wild type. Electrophoretic Mobility Shift Assay confirmed PDE191can bind to the3’-end DNA sequence of rpoA gene in vitro. Western blot showed theaccumulation level of RpoA protein was reduced in pde191-1. Meanwhile, Real TimeRT-PCR showed the levels of PEP controlled chloroplast genes were generallydown-regulated and most of the expression levels of other chloroplast genes weredisturbed. According to these data, we conclude that PDE191has a crucial role forArobidopsis chloroplast growth and development, probably by a way of terminatingtranscription of rpoA, and then regulating the activity of PEP, and finally controllingthe expression of chloroplast genes. The study of PDE191controlled transcriptiontermination of chloroplast genes is conductive to us a deep understanding the pocessof transcription termination of chloroplast genes controlled by nuclear genes.