1IYZ

Crystal Structures of the Quinone Oxidoreductase from Thermus thermophilus HB8 and Its Complex with NADPH

Summary for 1IYZ

• Entry DOI: 10.2210/pdb1iyz/pdb
• Descriptor: QUINONE OXIDOREDUCTASE, NADPH DIHYDRO-NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE (3 entities in total)
• Functional Keywords: protein-nadph complex, riken structural genomics/proteomics initiative, rsgi, structural genomics, oxidoreductase
• Biological source: Thermus thermophilus
• Total number of polymer chains: 1
• Total formula weight: 32872.08

Authors

Shimomura, Y.,Kakuta, Y.,Fukuyama, K.,RIKEN Structural Genomics/Proteomics Initiative (RSGI) (deposition date: 2002-09-17, release date: 2003-07-15, Last modification date: 2023-12-27)

Primary citation

Shimomura, Y.,Kakuta, Y.,Fukuyama, K.
Crystal Structures of the Quinone Oxidoreductase from Thermus thermophilus HB8 and Its Complex with NADPH: Implication for NADPH and Substrate Recognition
J.Bacteriol., 185:4211-4218, 2003

PubMed Abstract: The crystal structures of the zeta-crystalline-like soluble quinone oxidoreductase from Thermus thermophilus HB8 (QOR(Tt)) and of its complex with NADPH have been determined at 2.3- and 2.8-A resolutions, respectively. QOR(Tt) is composed of two domains, and its overall fold is similar to the folds of Escherichia coli quinone oxidoreductase (QOR(Ec)) and horse liver alcohol dehydrogenase. QOR(Tt) forms a homodimer in the crystal by interaction of the betaF-strands in domain II, forming a large beta-sheet that crosses the dimer interface. High thermostability of QOR(Tt) was evidenced by circular dichroic measurement. NADPH is located between the two domains in the QOR(Tt)-NADPH complex. The disordered segment involved in the coenzyme binding of apo-QOR(Tt) becomes ordered upon NADPH binding. The segment covers an NADPH-binding cleft and may serve as a lid. The 2'-phosphate group of the adenine of NADPH is surrounded by polar and positively charged residues in QOR(Tt), suggesting that QOR(Tt) binds NADPH more readily than NADH. The putative substrate-binding site of QOR(Tt), unlike that of QOR(Ec), is largely blocked by nearby residues, permitting access only to small substrates. This may explain why QOR(Tt) has weak p-benzoquinone reduction activity and is inactive with such large substrates of QOR(Ec) as 5-hydroxy-1,4-naphthoquinone and phenanthraquinone.

PubMed: 12837796
DOI: 10.1128/JB.185.14.4211-4218.2003

Experimental method

X-RAY DIFFRACTION (2.8 Å)