title: Binding and transcription of relaxed DNA templates by fractions of maize chloroplast extracts.
abstract: Preparations of partially purified chloroplast DNA-dependent RNA polymerase from maize and some other plants transcribe cloned chloroplast genes preferentially and much more actively from appropriately negatively supercoiled templates than from relaxed templates. We have found that the polymerase in such fractions does not bind to promoter regions of the maize chloroplast genes psbA and rbcL on small linear DNA fragments but that some protein(s) in unfractionated chloroplast extracts does bind. DEAE chromatography of the extracts has permitted the separation of a DNA-binding fraction from the bulk of the RNA polymerase activity. The binding fraction contains plastid RNA polymerase activity that is relatively independent of template topology.
authors.affiliation: Department of Cellular and Developmental Biology, Harvard University, Cambridge, MA 02138.
authors.forename: D
authors.initials: D
authors.lastname: Zaitlin
authors.forename: J
authors.initials: J
authors.lastname: Hu
authors.forename: L
authors.initials: L
authors.lastname: Bogorad
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002734:Chlorophyll / Q000235:genetics; D002736:Chloroplasts / Q000201:enzymology*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D005796:Genes; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D009710:Nucleotide Mapping; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins / Q000235:genetics; D010944:Plants / Q000201:enzymology / Q000235:genetics*; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000235:genetics; D013698:Templates, Genetic; D014158:Transcription, Genetic; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins; D012269:Ribosomal Proteins; C031798:ribosomal protein S4; D002734:Chlorophyll; D012321:DNA-Directed RNA Polymerases