Site-directed mutagenesis of conserved cysteine residues in NqrD and NqrE subunits of Na+-translocating NADH:quinone oxidoreductase.
Each of two hydrophobic subunits of Na+-translocating NADH:quinone oxidoreductase (NQR), NqrD and NqrE, contain a pair of strictly conserved cysteine residues within their transmembrane alpha-helices. Site-directed mutagenesis showed that substitutions of these residues in NQR of Vibrio harveyi blocked the Na+-dependent and 2-n-heptyl-4-hydroxyquinoline N-oxide-sensitive quinone reductase activity of the enzyme. However, these mutations did not affect the interaction of NQR with NADH and menadione. It was demonstrated that these conserved cysteine residues are necessary for the correct folding and/or the stability of the NQR complex. Mass and EPR spectroscopy showed that NQR from V. harveyi bears only a 2Fe-2S cluster as a metal-containing prosthetic group.
Fadeeva
M S
MS
Department of Bioinformatics and Bioengineering, Lomonosov Moscow State University, Moscow, Russia. masha@genebee.msu.ru
Bertsova
Y V
YV
Verkhovsky
M I
MI
Bogachev
A V
AV
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001692:Biological Transport; D003545:Cysteine / Q000737:chemistry* / Q000235:genetics; D008670:Metals / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics; D011808:Quinone Reductases / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012964:Sodium / Q000378:metabolism*; D014733:Vibrio / Q000201:enzymology*
D001426:Bacterial Proteins; D008670:Metals; D021122:Protein Subunits; D012964:Sodium; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases; D003545:Cysteine