Structural organization and transcription of plant mitochondrial and chloroplast genomes

摘要: Abstract Experimental evidence is presented showing that the plant mitochondrial and chloroplast genomes are multipartite and, besides a large circular genomic DNA, they contain subgenomic minicircular plasmid-like molecules. It demonstrated DNAs packaged into deoxynucleoprotein fibrils comprising nucleosome-like nucleomere-like globules; form loops rosette-like structures with central proteinaceous components. A similar structure characteristic of DNAs. The basic proteins involved in formation globules quite different from nuclear histones, indeed mitochondria chloroplasts also distinct. Some share common antigens E. coli HU protein. genetic code for genes universal. only codon now thought to be universal genome corrected during post-transcriptional mRNA editing. There two hexanucleotides promoters homologous sequences −10 −35 regions prokaryotic requisite transcription. Promoter responsible transcription regulation were not identified. Immunoelectronmicroscopic suggest RNA polymerases have β-subunit polymerase. shown intensely transcribed dark repressed by illumination. Electron microscopy about 70% numerous polymerase molecules dark, but this percentage falls 10–15% after light exposure.