First time at Proteopedia? Click on the green links: they change the 3D image. Click and drag the molecules. Proteopedia is a 3D, interactive encyclopedia of proteins, RNA, DNA and other molecules. With a free user account, you can edit pages in Proteopedia. Visit the Main Page to learn more.
|3sjj, resolution 2.38Å ()|
|Gene:||43, gp43 (Enterobacteria phage RB69)|
|Related:||3nci, 3cfo, 3cfp, 3cfr, 3s9h, 3scx, 3si6, 3snn|
RB69 DNA Polymerase Triple Mutant (L561A/S565G/Y567A) Ternary Complex with dUpNpp and a Deoxy-terminated Primer in the presence of Mn2+
We have captured a preinsertion ternary complex of RB69 DNA polymerase (RB69pol) containing the 3' hydroxyl group at the terminus of an extendable primer (ptO3') and a nonhydrolyzable 2'-deoxyuridine 5'-alpha,beta-substituted triphosphate, dUpXpp, where X is either NH or CH(2), opposite a complementary templating dA nucleotide residue. Here we report four structures of these complexes formed by three different RB69pol variants with catalytically inert Ca(2+) and four other structures with catalytically competent Mn(2+) or Mg(2+). These structures provide new insights into why the complete divalent metal-ion coordination complexes at the A and B sites are required for nucleotidyl transfer. They show that the metal ion in the A site brings ptO3' close to the alpha-phosphorus atom (Palpha) of the incoming dNTP to enable phosphodiester bond formation through simultaneous coordination of both ptO3' and the nonbridging Sp oxygen of the dNTP's alpha-phosphate. The coordination bond length of metal ion A as well as its ionic radius determines how close ptO3' can approach Palpha. These variables are expected to affect the rate of bond formation. The metal ion in the B site brings the pyrophosphate product close enough to Palpha to enable pyrophosphorolysis and assist in the departure of the pyrophosphate. In these dUpXpp-containing complexes, ptO3' occupies the vertex of a distorted metal ion A coordination octahedron. When ptO3' is placed at the vertex of an undistorted, idealized metal ion A octahedron, it is within bond formation distance to Palpha. This geometric relationship appears to be conserved among DNA polymerases of known structure.
Structural Insights into Complete Metal Ion Coordination from Ternary Complexes of B Family RB69 DNA Polymerase., Xia S, Wang M, Blaha G, Konigsberg WH, Wang J, Biochemistry. 2011 Oct 25;50(42):9114-24. Epub 2011 Sep 29. PMID:21923197
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.