1UT5

Divalent metal ions (manganese) bound to T5 5'-exonuclease

Summary for 1UT5

• Entry DOI: 10.2210/pdb1ut5/pdb
• Related: 1EXN 1J5F 1UT8 1XO1
• Descriptor: EXODEOXYRIBONUCLEASE, MANGANESE (II) ION (3 entities in total)
• Functional Keywords: hydrolase, exonuclease, nuclease
• Biological source: BACTERIOPHAGE T5
• Total number of polymer chains: 2
• Total formula weight: 67148.55

Authors

Ceska, T.A.,Sayers, J.R.,Suck, D. (deposition date: 2003-12-04, release date: 2004-02-05, Last modification date: 2023-12-13)

Primary citation

Feng, M.,Patel, D.,Dervan, J.,Ceska, T.A.,Suck, D.,Haq, I.,Sayers, J.R.
Roles of Divalent Metal Ions in Flap Endonuclease-Substrate Interactions
Nat.Struct.Mol.Biol., 11:450-, 2004

PubMed Abstract: Flap endonucleases (FENs) have essential roles in DNA processing. They catalyze exonucleolytic and structure-specific endonucleolytic DNA cleavage reactions. Divalent metal ions are essential cofactors in both reactions. The crystal structure of FEN shows that the protein has two conserved metal-binding sites. Mutations in site I caused complete loss of catalytic activity. Mutation of crucial aspartates in site II abolished exonuclease action, but caused enzymes to retain structure-specific (flap endonuclease) activity. Isothermal titration calorimetry revealed that site I has a 30-fold higher affinity for cofactor than site II. Structure-specific endonuclease activity requires binding of a single metal ion in the high-affinity site, whereas exonuclease activity requires that both the high- and low-affinity sites be occupied by divalent cofactor. The data suggest that a novel two-metal mechanism operates in the FEN-catalyzed exonucleolytic reaction. These results raise the possibility that local concentrations of free cofactor could influence the endo- or exonucleolytic pathway in vivo.

PubMed: 15077103
DOI: 10.1038/NSMB754

Experimental method

X-RAY DIFFRACTION (2.75 Å)