title: A new protein subunit k for RNA polymerase from Xanthomonas campestris pv. oryzae.
abstract: During the purification of RNA polymerase from Xanthomonas campestris pv. oryzae, a new subunit named k was found to be associated with this enzyme. The removal of subunit k from holoenzyme by DEAE-cellulose column chromatography results in a decrease in specific activity of the enzyme. The readdition of subunit k to subunit k-depleted holoenzyme results in restoration of enzymatic activity. Subunit k increase the activity of RNA polymerase; the activation was in proportion to the concentration of subunit k added. Antiserum against holoenzyme devoid of subunit k was prepared. This antiserum did not react with purified subunit k; therefore, subunit k may not be the proteolytic fragment of the beta, beta', sigma, or alpha subunit. When this antiserum was used to precipitate RNA polymerase obtained from a crude extract of bacterial cells, subunit k was coprecipitated as determined by sodium dodecyl sulfate gel electrophoretic analysis. The molecular mass of subunit k is approximately 29 kDa, and the molar ratio of beta:beta':sigma:alpha:k was estimated to be 1:1:1:2:4. When native Xp10 DNA was used as template, subunit k stimulated subunit k-depleted holoenzyme, but not core enzyme. When the synthetic polynucleotide poly[d(A-T)] was used, subunit k activated both subunit k-depleted holoenzyme and core enzyme. Subunit k also activated the binding of RNA polymerase to template DNA.
authors.affiliation: Department of Botany, National Taiwan University, Taipei, Republic of China.
authors.forename: C K
authors.initials: CK
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Tu
authors.forename: T T
authors.initials: TT
authors.lastname: Kuo
mesh_terms: D002845:Chromatography; D004247:DNA / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D007163:Immunosorbent Techniques; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments; D011067:Poly dA-dT / Q000378:metabolism; D013329:Structure-Activity Relationship; D013698:Templates, Genetic; D014974:Xanthomonas / Q000201:enzymology*
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; D011067:Poly dA-dT; D004247:DNA; D012321:DNA-Directed RNA Polymerases