title: Crystal structure of Thermus aquaticus core RNA polymerase at 3.3 A resolution.
abstract: The X-ray crystal structure of Thermus aquaticus core RNA polymerase reveals a "crab claw"-shaped molecule with a 27 A wide internal channel. Located on the back wall of the channel is a Mg2+ ion required for catalytic activity, which is chelated by an absolutely conserved motif from all bacterial and eukaryotic cellular RNA polymerases. The structure places key functional sites, defined by mutational and cross-linking analysis, on the inner walls of the channel in close proximity to the active center Mg2+. Further out from the catalytic center, structural features are found that may be involved in maintaining the melted transcription bubble, clamping onto the RNA product and/or DNA template to assure processivity, and delivering nucleotide substrates to the active center.
authors.affiliation: The Rockefeller University, New York, New York 10021, USA.
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: E A
authors.initials: EA
authors.lastname: Campbell
authors.forename: L
authors.initials: L
authors.lastname: Minakhin
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.forename: K
authors.initials: K
authors.lastname: Severinov
authors.forename: S A
authors.initials: SA
authors.lastname: Darst
mesh_terms: D020134:Catalytic Domain; D002736:Chloroplasts / Q000201:enzymology; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D005786:Gene Expression Regulation; D008958:Models, Molecular; D009711:Nucleotides / Q000378:metabolism; D011387:Prokaryotic Cells / Q000201:enzymology; D017433:Protein Structure, Secondary; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA; D013329:Structure-Activity Relationship; D013824:Thermus / Q000201:enzymology*; D014158:Transcription, Genetic
chemical_list: D003432:Cross-Linking Reagents; D009711:Nucleotides; D012321:DNA-Directed RNA Polymerases