Barley (Hordeum vulgare) leaf segments unroll and green when illuminated. Illuminated segments also have an increased capacity for RNA synthesis. Part of this increased RNA synthesis may be attributed to an increased RNA polymerase activity. In addition, following illumination there is an increased formation of polysomes.Analyses of RNA synthesized during illumination showed that the radioactiv...

The intrachloroplastic localization of post-transcriptional gene expression steps represents one key determinant for the regulation of chloroplast development. We have characterized an RNA binding protein of 63 kDa (RBP63) from Chlamydomonas reinhardtii chloroplasts, which cofractionates with stromal thylakoid membranes. Solubility properties suggest that RBP63 is a peripheral membrane protein....

Light plays a key role in the regulation of many physiological processes required for plant and chloroplast development. Plant cryptochromes (crys) play an important role in monitoring, capturing, and transmitting the light stimuli. In this study, we analyzed the effects of CRY2 overexpression on transcription of tomato chloroplast genome by a tiling array, containing about 90 000 overlapping p...

C-to-U editing of transcripts in plant organelles is carried out by small (<400 kD) protein complexes called editosomes. Recognition of the proper C target for editing is mediated by pentatricopeptide repeat (PPR) containing proteins that recognize cis-elements. Members of two additional gene families, the RIP/MORF and ORRM families, have each been found to be required for editing of particular...

The biogenesis of the photosynthetic electron transfer chain in the thylakoid membranes requires the concerted expression of genes in the chloroplast and the nucleus. Chloroplast gene expression is subjected to anterograde control by a battery of nucleus-encoded proteins that are imported in the chloroplast, where they mostly intervene at posttranscriptional steps. Using a new genetic screen, w...

Chloroplast translation is mediated by nucleus-encoded factors that interact with distinct cis-acting RNA elements. A U-rich sequence within the 5' untranslated region of the psbD mRNA has previously been shown to be required for its translation in Chlamydomonas reinhardtii. By using UV cross-linking assays, we have identified a 40-kDa RNA binding protein, which binds to the wild-type psbD lead...

In the past two decades, chloroplast genetic engineering has been advanced to achieve high-level protein accumulation but not for down-regulation of targeted genes. Therefore, in this report, lepidopteran chitin synthase (Chi), cytochrome P450 monooxygenase (P450) and V-ATPase dsRNAs were expressed via the chloroplast genome to study RNA interference (RNAi) of target genes in intended hosts. PC...

Maturation of chloroplast ribosomal RNAs (rRNAs) comprises several endoribonucleolytic and exoribonucleolytic processing steps. However, little is known about the specific enzymes involved and the cleavage steps they catalyze. Here, we report the functional characterization of the single Arabidopsis (Arabidopsis thaliana) gene encoding a putative YbeY endoribonuclease. AtYbeY null mutants are s...

Both one- and two-dimensional peptide mapping techniques have been used to compare the 180-kilodalton subunits from maize chloroplast and type II nuclear DNA-dependent RNA polymerases (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6). Despite their similar molecular mass, these 180-kilodalton subunits are not the same. Also, two-dimensional tryptic maps of the 160-, 43-, and 28-ki...

Chloroplasts are multifunctional organelles whose morphology is affected by environmental stresses. Although the three-dimensional (3D) architecture of thylakoid membranes has been reported previously, a 3D visualization of chloroplast under stress has not been explored. In this work, we used a positive-strand RNA ((+)RNA) virus, barley stripe mosaic virus (BSMV) to observe chloroplast structur...