title: Subunit proximity in the H+-translocating NADH-quinone oxidoreductase probed by zero-length cross-linking.
abstract: The proton-translocating NADH-quinone oxidoreductase (NDH-1) of Paracoccus denitrificans is composed of 14 different subunits (designated Nqo1-14), seven of which are located in the membrane domain and the other seven in the peripheral domain. It has been previously reported that membrane domain subunit Nqo7 (ND3) directly interacts with peripheral subunit Nqo6 (PSST) by using a cross-linker, m-maleimidobenzoyl-N-hydrosuccinimide ester, and heterologous expression [Di Bernardo, S., and Yagi, T. (2001) FEBS Lett. 508, 385-388]. To further explore the near-neighbor relationship of the subunits, a zero-length cross-linker, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC), and the Paracoccus membranes were used, and the cross-linked products were examined with antibodies specific to subunits Nqo1-11. The Nqo6 subunit was cross-linked to subunit Nqo9 (TYKY). In addition, a ternary product of Nqo3 (75k), Nqo6, and Nqo7 and binary products of Nqo3 and Nqo6 and of Nqo6 and Nqo7 were observed, but a binary product of Nqo3 and Nqo7 was not detected. The Nqo4 (49k) subunit was found to be associated with the Nqo7 subunit. Furthermore, Paracoccus subunits Nqo3, Nqo6, and Nqo7 were heterologously coexpressed in Escherichia coli, and EDC cross-linking experiments were carried out using the E. coli membranes expressing these three subunits. The results were the same as those obtained with Paracoccus membranes. On the basis of the data, subunit arrangements of NDH-1 were discussed.
authors.affiliation: Division of Biochemistry, Department of Molecular and Experimental Medicine, MEM-256, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Mou-Chieh
authors.initials: MC
authors.lastname: Kao
authors.forename: Akemi
authors.initials: A
authors.lastname: Matsuno-Yagi
authors.forename: Takao
authors.initials: T
authors.lastname: Yagi
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000031:analogs & derivatives / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D010231:Paracoccus denitrificans / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics; D006180:Proton-Translocating ATPases / Q000737:chemistry; D011808:Quinone Reductases / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D021122:Protein Subunits; D011994:Recombinant Proteins; C041829:1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide methiodide; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases; D006180:Proton-Translocating ATPases; D005022:Ethyldimethylaminopropyl Carbodiimide