Subunit III of cytochrome c oxidase influences the conformation of subunits I and II

An infrared study

Izaskun Echabe, Tuomas Haltia, Ernesto I Freire, Félix M. Goñi, José Luis R Arrondo

Research output: Contribution to journalArticle

Abstract

The secondary structure of wild-type Paracoccus denitrificans cytochrome c oxidase obtained by decomposition of the infrared amide I band contains 44% α-helix, 18% β-sheet, 14% β-turns, 18% loops, and 6% nonordered segments. The mutant lacking subunit III presents a small but significant increase (from 18% to 24%) in the percentage of loops and slight differences in the other components. Using band/area ratios and tyrosine side chain absorption as an inner standard, it is shown that in the absence of subunit III the structure of subunits I and II is altered although no changes in their α-helix or β-sheet content are observed. In the bacterial oxidase, thermal infrared studies show a complex denaturation pattern characterized by the presence of a partially denatured intermediate state. Of the seven predicted subunit III α-helices, only four are resistant toward the thermal challenge and behave as expected for typical transmembrane helices. The observation that the absence of subunit III influences the conformation of loop regions in the two other subunits suggests that part of the interaction surface between subunit III and the catalytic subunits might be located outside the lipid bilayer.

Original languageEnglish (US)
Pages (from-to)13565-13569
Number of pages5
JournalBiochemistry®
Volume34
Issue number41
StatePublished - 1995

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Electron Transport Complex IV
Conformations
Hot Temperature
Paracoccus denitrificans
Infrared radiation
Denaturation
Lipid bilayers
Lipid Bilayers
Amides
Tyrosine
Catalytic Domain
Oxidoreductases
Decomposition

ASJC Scopus subject areas

  • Biochemistry

Cite this

Echabe, I., Haltia, T., Freire, E. I., Goñi, F. M., & Arrondo, J. L. R. (1995). Subunit III of cytochrome c oxidase influences the conformation of subunits I and II: An infrared study. Biochemistry®, 34(41), 13565-13569.

Subunit III of cytochrome c oxidase influences the conformation of subunits I and II : An infrared study. / Echabe, Izaskun; Haltia, Tuomas; Freire, Ernesto I; Goñi, Félix M.; Arrondo, José Luis R.

In: Biochemistry®, Vol. 34, No. 41, 1995, p. 13565-13569.

Research output: Contribution to journalArticle

Echabe, I, Haltia, T, Freire, EI, Goñi, FM & Arrondo, JLR 1995, 'Subunit III of cytochrome c oxidase influences the conformation of subunits I and II: An infrared study', Biochemistry®, vol. 34, no. 41, pp. 13565-13569.
Echabe, Izaskun ; Haltia, Tuomas ; Freire, Ernesto I ; Goñi, Félix M. ; Arrondo, José Luis R. / Subunit III of cytochrome c oxidase influences the conformation of subunits I and II : An infrared study. In: Biochemistry®. 1995 ; Vol. 34, No. 41. pp. 13565-13569.
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