4rnp is a 3 chain structure with sequence from Enterobacteria phage t7. This structure supersedes the now removed PDB entries and 2rnp. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
[RPOL_BPT7] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Responsible for the transcription of the late genes of T7. It is rifampicin-resistant. It recognizes a specific promoter sequence, unwinds the double-stranded RNA to expose the coding strand for templating, initiates transcription preferentially with a purine.
The crystal structure of T7 RNA polymerase reveals a molecule organized around a cleft that can accommodate a double-stranded DNA template. A portion (approximately 45%) of the molecule displays extensive structural homology to the polymerase domain of Klenow fragment and more limited homology to the human immunodeficiency virus HIV-1 reverse transcriptase. A comparison of the structures and sequences of these polymerases identifies structural elements that may be responsible for discriminating between ribonucleotide and deoxyribonucleotide substrates, and RNA and DNA templates. The relative locations of the catalytic site and a specific promoter recognition residue allow the orientation of the polymerase on the template to be defined.
Crystal structure of bacteriophage T7 RNA polymerase at 3.3 A resolution.,Sousa R, Chung YJ, Rose JP, Wang BC Nature. 1993 Aug 12;364(6438):593-9. PMID:7688864
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.