3q24
From Proteopedia
X-ray crystal structure of the N4 mini-VRNAP and P2_7a promoter transcription initiation complex with pppGpG and pyrophosphate: product complex
Structural highlights
FunctionRPOLV_BPN4 DNA-dependent RNA polymerase, which is injected into the host upon infection and transcribes the phage early genes from promoters that have a 5-bp stem-3 nt loop hairpin structure.[1] [2] Publication Abstract from PubMedWe have determined the X-ray crystal structures of the pre- and postcatalytic forms of the initiation complex of bacteriophage N4 RNA polymerase that provide the complete set of atomic images depicting the process of transcript initiation by a single-subunit RNA polymerase. As observed during T7 RNA polymerase transcript elongation, substrate loading for the initiation process also drives a conformational change of the O helix, but only the correct base pairing between the +2 substrate and DNA base is able to complete the O-helix conformational transition. Substrate binding also facilitates catalytic metal binding that leads to alignment of the reactive groups of substrates for the nucleotidyl transfer reaction. Although all nucleic acid polymerases use two divalent metals for catalysis, they differ in the requirements and the timing of binding of each metal. In the case of bacteriophage RNA polymerase, we propose that catalytic metal binding is the last step before the nucleotidyl transfer reaction. X-ray crystal structures elucidate the nucleotidyl transfer reaction of transcript initiation using two nucleotides.,Gleghorn ML, Davydova EK, Basu R, Rothman-Denes LB, Murakami KS Proc Natl Acad Sci U S A. 2011 Feb 14. PMID:21321236[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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