Studies on a thermophilic RNA polymerase which is active only on poly d(A-T) and poly dAdT.
Two types of RNA polymerases [EC 2.7.7.6], polymerases A and B, exist in thermophilic bacteria, Thermus thermophilus HB8. Polymerase B is apparently like the core enzyme of polymerase A but is active only when an alternating copolymer of deoxyadenylic and deoxythymidylic acids (poly d(A-T)) or a mixture of homopolymers of deoxyadenylic acid and deoxythymidylic acid (poly dAdT) is used as a template. Polymerase B was further characterized to elucidate its relation to polymerase A and to determine why it is inactive on natural DNA's. 1. Polymerase B did not show pyrophosphate exchange activity. Dinucleoside monophosphates did not activate the RNA-synthesizing activity. The results suggested that polymerase B had no initiation and presumably no elongation activities. 2. Polymerase B had about 6 times greater affinity to DNA than polymerase A. The binding of polymerase B to DNA was, however, reversible. The complex of DNA with polymerase A was stable and the polymerase was not removed from the initial complex even when a large amount of DNA was added. 3. E. coli sigma subunit could not stimulate the activity of polymerase B toward DNA's. 4. Polymerase B could utilize poly d(A-T) and poly dAdT as templates, but could not use Bacillus cereus DNA though the structure is reported to be similar to that of poly d(A-T).
D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D003090:Coliphages; D004247:DNA / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology*; D011071:Poly T / Q000378:metabolism; D011089:Polydeoxyribonucleotides / Q000378:metabolism*; D013950:Thymus Gland
D000227:Adenine Nucleotides; D004279:DNA, Viral; D011756:Diphosphates; D011089:Polydeoxyribonucleotides; D011071:Poly T; D000255:Adenosine Triphosphate; D004247:DNA; D012321:DNA-Directed RNA Polymerases