4c3h
From Proteopedia
Structure of 14-subunit RNA polymerase I at 3.27 A resolution, crystal form C2-93
Structural highlights
FunctionRPA1_YEAST DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Largest and catalytic core component of RNA polymerase I which synthesizes ribosomal RNA precursors. Forms the polymerase active center together with the second largest subunit. A single stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol I. A bridging helix emanates from RPA1 and crosses the cleft near the catalytic site and is thought to promote translocation of Pol I by acting as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations at each step of nucleotide addition (By similarity). Publication Abstract from PubMedProtein biosynthesis depends on the availability of ribosomes, which in turn relies on ribosomal RNA production. In eukaryotes, this process is carried out by RNA polymerase I (Pol I), a 14-subunit enzyme, the activity of which is a major determinant of cell growth. Here we present the crystal structure of Pol I from Saccharomyces cerevisiae at 3.0 A resolution. The Pol I structure shows a compact core with a wide DNA-binding cleft and a tightly anchored stalk. An extended loop mimics the DNA backbone in the cleft and may be involved in regulating Pol I transcription. Subunit A12.2 extends from the A190 jaw to the active site and inserts a transcription elongation factor TFIIS-like zinc ribbon into the nucleotide triphosphate entry pore, providing insight into the role of A12.2 in RNA cleavage and Pol I insensitivity to alpha-amanitin. The A49-A34.5 heterodimer embraces subunit A135 through extended arms, thereby contacting and potentially regulating subunit A12.2. Crystal structure of the 14-subunit RNA polymerase I.,Fernandez-Tornero C, Moreno-Morcillo M, Rashid UJ, Taylor NM, Ruiz FM, Gruene T, Legrand P, Steuerwald U, Muller CW Nature. 2013 Oct 31;502(7473):644-9. doi: 10.1038/nature12636. Epub 2013 Oct 23. PMID:24153184[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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