Direct interaction between a membrane domain subunit and a connector subunit in the H(+)-translocating NADH-quinone oxidoreductase.
When Paracoccus denitrificans membranes were treated with a crosslinker, m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS), a cross-linked product of M(r) approximately 31 kDa was found which reacted with antibodies against the hydrophobic subunit Nqo7 and the connector subunit Nqo6. NaI treatment of the Paracoccus membranes before, but not after, the crosslinking step prevented the formation of the 31 kDa band. When Nqo7 and Nqo6 were coexpressed in Escherichia coli, both subunits were located in the membrane fraction. MBS treatment of the E. coli membranes generated the 31 kDa band as in the Paracoccus membranes. These results indicate that Nqo7 interacts with probable N2-binding Nqo6.
Di Bernardo
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S
MEM-256, Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 Torrey Pines Rd., La Jolla, CA 92037, USA.
Yagi
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T
D000906:Antibodies; D002462:Cell Membrane / Q000201:enzymology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D010231:Paracoccus denitrificans / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D011808:Quinone Reductases / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013388:Succinimides / Q000494:pharmacology
D000906:Antibodies; D003432:Cross-Linking Reagents; D021122:Protein Subunits; D011994:Recombinant Proteins; D013388:Succinimides; C072252:m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases