2ihn | pdb_00002ihn

Co-crystal of Bacteriophage T4 RNase H with a fork DNA substrate

spinqualitylabelsall models 2ihn, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2ihn is a 3 chain structure with sequence from Escherichia virus T4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RNH_BPT4 5' to 3' exonuclease that removes the pentamer RNA primers from DNA chains initiated by the T4 primase-helicase. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Bacteriophage T4 RNase H, a flap endonuclease-1 family nuclease, removes RNA primers from lagging strand fragments. It has both 5' nuclease and flap endonuclease activities. Our previous structure of native T4 RNase H (PDB code 1TFR) revealed an active site composed of highly conserved Asp residues and two bound hydrated magnesium ions. Here, we report the crystal structure of T4 RNase H in complex with a fork DNA substrate bound in its active site. This is the first structure of a flap endonuclease-1 family protein with its complete branched substrate. The fork duplex interacts with an extended loop of the helix-hairpin-helix motif class 2. The 5' arm crosses over the active site, extending below the bridge (helical arch) region. Cleavage assays of this DNA substrate identify a primary cut site 7-bases in from the 5' arm. The scissile phosphate, the first bond in the duplex DNA adjacent to the 5' arm, lies above a magnesium binding site. The less ordered 3' arm reaches toward the C and N termini of the enzyme, which are binding sites for T4 32 protein and T4 45 clamp, respectively. In the crystal structure, the scissile bond is located within the double-stranded DNA, between the first two duplex nucleotides next to the 5' arm, and lies above a magnesium binding site. This complex provides important insight into substrate recognition and specificity of the flap endonuclease-1 enzymes. Crystal structure of bacteriophage T4 5' nuclease in complex with a branched DNA reveals how flap endonuclease-1 family nucleases bind their substrates.,Devos JM, Tomanicek SJ, Jones CE, Nossal NG, Mueser TC J Biol Chem. 2007 Oct 26;282(43):31713-24. Epub 2007 Aug 9. PMID:17693399 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease 3D structures

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