1exn | pdb_00001exn
T5 5'-EXONUCLEASE
Structural highlights
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 PubMedTHE 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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