Crystal Structure of a New Type of NADPH-Dependent Quinone Oxidoreductase (QOR2) from Escherichia coli

In Kwon Kim, Hyung Soon Yim, Min Kyu Kim, Dong Won Kim, Young Min Kim, Sun Shin Cha, Sa Ouk Kang

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Escherichia coli QOR2 [NAD(P)H-dependent quinone oxidoreductase; a ytfG gene product], which catalyzes two-electron reduction of methyl-1,4-benzoquinone, is a new type of quinone-reducing enzyme with distinct primary sequence and oligomeric conformation from previously known quinone oxidoreductases. The crystal structures of native QOR2 and the QOR2-NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) complex reveal that QOR2 consists of two domains (N-domain and C-domain) resembling those of NmrA, a negative transcriptional regulator that belongs to the short-chain dehydrogenase/reductase family. The N-domain, which adopts the Rossmann fold, provides a platform for NADPH binding, whereas the C-domain, which contains a hydrophobic pocket connected to the NADPH-binding site, appears to play important roles in substrate binding. Asn143 near the NADPH-binding site has been identified to be involved in substrate binding and catalysis from structural and mutational analyses. Moreover, compared with wild-type strain, the qor2-overexpressing strain shows growth retardation and remarkable decrease in several enzymes involved in carbon metabolism, suggesting that QOR2 could play some physiological roles in addition to quinone reduction.

Original languageEnglish
Pages (from-to)372-384
Number of pages13
JournalJournal of Molecular Biology
Volume379
Issue number2
DOIs
StatePublished - 29 May 2008

Keywords

  • NAD(P)H-dependent quinone oxidoreductase
  • QOR2
  • carbon metabolism
  • short-chain dehydrogenase/reductase family
  • transcriptional regulator

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