The Protein Journal

, Volume 26, Issue 7, pp 517–521

The Role of Phe181 in the Hexamerization of Helicobacter pylori Quinolinate Phosphoribosyltransferase



Quinolinic acid phosphoribosyltransferase (QAPRTase; NadC) catalyzes an indispensable step in NAD biosynthesis, one that is essential for cell survival in prokaryotes, which makes it an attractive target for antibacterial drug therapy. We recently reported the crystal structures of Helicobacter pylori QAPRTase with bound quinolinic acid, nicotinamide mononucleotide, and phthalic acid. The enzyme exists as a hexamer organized as a trimer of dimers, which is essential for full enzymatic activity. The loop between helix α7 and strand β8 contributes significantly to the hydrophobic dimer-dimer interactions. Phe181Pro mutation within the α7-β8 loop disrupts the hexamerization of QAPRTase, and the resultant dimer shows dramatically reduced protein stability and no activity. Our findings thus suggest that compounds able to disrupt its proper oligomerization could potentially function as selective inhibitors of Helicobacter pylori QAPRTase and represent a novel set of antibacterial agents.


Quinolinate phosphoribosyltransferase Hexamerization Drug target Helicobacter pylori 



Quinolinate phosphoribosyltransferase


Nicotinamide adenine dinucleotide


Quinolinic acid




Nicotinic acid mononucleotide


Nicotinate phosphoribosyltransferase


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • M.-K. Kim
    • 1
  • G. B. Kang
    • 1
  • W. K. Song
    • 1
  • S. H. Eom
    • 1
  1. 1.Department of Life ScienceGwangju Institute of Science & TechnologyGwangjuRepublic of Korea

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