1exn

T5 5'-EXONUCLEASE

spinqualitylabelsall models 1exn, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1exn is a 2 chain structure with sequence from Bpt5. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: MSE Gene: D15 (BPT5) Activity: Exodeoxyribonuclease (lambda-induced), with EC number 3.1.11.3 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [EXO5_BPT5] 5'-exonucleolytic degradation of double-stranded (ds) DNA. Can also cleave bifurcated nucleic acids such as flap and pseudo-Y substrates in a structure-specific manner. This requires free 5' single-stranded (ss) ends and cleaves at the ds/ss junction. Binds DNA pseudo-Y substrates with a dissociation constant of 5 nM. 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 THE 5'-exonucleases are enzymes that are essential for DNA replication and repair. As well as their exonucleolytic action, removing nucleotides from the 5'-end of nucleic acid molecules such as Okazaki fragments, many 5'-3'-exonucleases have been shown to possess endonucleolytic activities. T5 5'-3'-exonuclease shares many similarities with the amino terminal of eubacterial DNA polymerases, although, unlike eubacteria, phages such as T5, T4 and T7 express polymerase and 5'-exonuclease proteins from separate genes. Here we report the 2.5-A crystal structure of the phage T5 5'-exonuclease, which reveals a helical arch for binding DNA. We propose a model consistent with a threading mechanism in which single-stranded DNA could slide through the arch, which is formed by two helices, one containing positively charged, and the other hydrophobic, residues. The active site is at the base of the arch, and contains two metal-binding sites. A helical arch allowing single-stranded DNA to thread through T5 5'-exonuclease.,Ceska TA, Sayers JR, Stier G, Suck D Nature. 1996 Jul 4;382(6586):90-3. PMID:8657312 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Exonuclease Sand box 211

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