1exn
From Proteopedia
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T5 5'-EXONUCLEASE
Overview
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.
About this Structure
1EXN is a Single protein structure of sequence from Pseudomonas phage d3112. Active as Exodeoxyribonuclease (lambda-induced), with EC number 3.1.11.3 Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Tue Nov 20 14:24:29 2007
