PMID: 12352955 , Related PDB id: 1MH9

Authors:

Rinaldo-Matthis A, Rampazzo C, Reichard P, Bianchi V, Nordlund P

Title:

Crystal structure of a human mitochondrial deoxyribonucleotidase.

Journal:

Nat Struct Biol. 2002 Oct;9(10):779-87.

Abstract:

5' nucleotidases are ubiquitous enzymes that dephosphorylate nucleoside monophosphates and participate in the regulation of nucleotide pools. The mitochondrial 5'-(3') deoxyribonucleotidase (dNT-2) specifically dephosphorylates dUMP and dTMP, thereby protecting mitochondrial DNA replication from excess dTTP. We have solved the structure of dNT-2, the first of a mammalian 5' nucleotidase. The structure reveals a relationship to the HAD family, members of which use an aspartyl nucleophile as their common catalytic strategy, with a phosphoserine phosphatase as the most similar neighbor. A structure-based sequence alignment of dNT-2 with other 5' nucleotidases also suggests a common origin for these enzymes. Here we study the structures of dNT-2 in complex with bound phosphate and beryllium trifluoride plus thymidine as model for a phosphoenzyme-product complex. Based on these structures, determinants for substrate specificity recognition and the catalytic action of dNT-2 are outlined.