Structural and kinetic characterization of quinolinate phosphoribosyltransferase (hQPRTase) from Homo sapiens

Huanting Liu, Kerry Woznica, Gemma Catton, Amanda Crawford, Nigel Botting, James H. Naismith

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38 Citations (Scopus)

Abstract

Human quinolinate phosphoribosyltransferase (EC 2.4.2.19) (hQPRTase) is a member of the type 11 phosphoribosyltransferase family involved in the catabolism of quinolinic acid (QA). It catalyses the formation of nicotinic acid mononucleotide from quinolinic acid, which involves a phosphoribosyl transfer reaction followed by decarboxylation. hQPRTase has been implicated in a number of neurological conditions and in order to study it further, we have carried out structural and kinetic studies on recombinant hQPRTase. The structure of the fully active enzyme overexpressed in Escherichia coli was solved using multiwavelength methods to a resolution of 2.0 angstrom. hQPRTase has a alpha/beta barrel fold sharing a similar overall structure with the bacterial QPRTases. The active site of hQPRTase is located at an alpha/beta open sandwich structure that serves as a cup for the alpha/beta barrel of the adjacent subunit with a QA binding site consisting of three arginine residues (R102, R138 and R161) and two lysine residues (K139 and K171). Mutation of these residues affected substrate binding or abolished the enzymatic activity. The kinetics of the human enzyme are different to the bacterial enzymes studied, hQPRTase is inhibited competitively and noncompetitively by one of its substrates, 5-phosphoribosylpyrophosphate (PRPP). The human enzyme adopts a hexameric arrangement, which places the active sites in close proximity to each other. (c) 2007 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)755-763
Number of pages9
JournalJournal of Molecular Biology
Volume373
DOIs
Publication statusPublished - 26 Oct 2007

Keywords

  • NAD biosynthesis
  • Homo sapiens quinolinate phosphoribosyltransferase
  • quinolinic acid
  • 5-phosphoribosylpyrophosphate
  • nicotinic acid mononucleotide
  • MUSHROOM LENTINUS-EDODES
  • ACID PHOSPHORIBOSYLTRANSFERASE
  • CRYSTAL-STRUCTURE
  • RAT-BRAIN
  • OROTATE PHOSPHORIBOSYLTRANSFERASE
  • HUNTINGTONS-DISEASE
  • PURIFICATION
  • TRANSFERASE
  • LIVER
  • CRYSTALLIZATION

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  • BBSRC BBS/B/14426: SPORT

    Naismith, J.

    BBSRC

    18/10/0430/04/12

    Project: Standard

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