HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 51, 36914-36922, December 21, 2007

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 282/51/36914    most recent M707855200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Torres-Bacete, J. Articles by Yagi, T. Search for Related Content PubMed PubMed Citation Articles by Torres-Bacete, J. Articles by Yagi, T. Social Bookmarking                      What's this?

Characterization of the NuoM (ND4) Subunit in Escherichia coli NDH-1

CONSERVED CHARGED RESIDUES ESSENTIAL FOR ENERGY-COUPLED ACTIVITIES^*

From the Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037

The proton-translocating NADH-quinone (Q) oxidoreductase (NDH-1) from Escherichia coli is composed of two segments: a peripheral arm and a membrane arm. The membrane arm contains 7 hydrophobic subunits. Of these subunits, NuoM, a homolog of the mitochondrial ND4 subunit, is proposed to be involved in proton translocation and Q-binding. Therefore, we conducted site-directed mutation of 15 amino acid residues of NuoM and investigated their properties. In all mutants, the assembly of the whole enzyme seemed intact. Mutation of highly conserved Glu¹⁴⁴ and Lys²³⁴ leads to almost total elimination of energy-transducing NDH-1 activities as well as increased production of superoxide radicals. Their NADH dehydrogenase activities were almost normal. Because these two residues are predicted to be located in the transmembrane segments of NuoM, the results strongly suggest that they participate in proton translocation. Although it is hypothesized that His interacts with a Q head group, mutations at four His moderately inhibited NDH-1 activities and had almost no effect on the K_m values for Q or IC₅₀ values of capsaicin-40, a competitive inhibitor for the Q binding site. The data suggest that these His are not involved in the catalytic Q-binding. Functional roles of NuoM and advantages of NDH-1 research as a model for mitochondrial complex I study have been discussed.

Received for publication, September 19, 2007 , and in revised form, October 17, 2007.

^* This work was supported by National Institutes of Health R01GM033712 (to T. Y. and A. M.-Y.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Table S1 and Fig. S1.

¹ To whom correspondence should be addressed: Division of Biochemistry, Dept. of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037. Fax: 858-784-2054; E-mail: yagi{at}scripps.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				Y. Kajiyama, M. Otagiri, J. Sekiguchi, T. Kudo, and S. Kosono The MrpA, MrpB and MrpD subunits of the Mrp antiporter complex in Bacillus subtilis contain membrane-embedded and essential acidic residues Microbiology, July 1, 2009; 155(7): 2137 - 2147. [Abstract] [Full Text] [PDF]

				P. K. Sinha, J. Torres-Bacete, E. Nakamaru-Ogiso, N. Castro-Guerrero, A. Matsuno-Yagi, and T. Yagi Critical Roles of Subunit NuoH (ND1) in the Assembly of Peripheral Subunits with the Membrane Domain of Escherichia coli NDH-1 J. Biol. Chem., April 10, 2009; 284(15): 9814 - 9823. [Abstract] [Full Text] [PDF]