Mutation of a single residue in the ba 3 oxidase specifically impairs protonation of the pump site

von Ballmoos, Christoph; Gonska, Nathalie; Lachmann, Peter; Gennis, Robert B.; Ädelroth, Pia; Brzezinski, Peter (2015). Mutation of a single residue in the ba 3 oxidase specifically impairs protonation of the pump site. Proceedings of the National Academy of Sciences of the United States of America - PNAS, 112(11), pp. 3397-3402. National Academy of Sciences NAS 10.1073/pnas.1422434112

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The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound protein complex that couples electron transfer to O2 to proton translocation across the membrane. To elucidate the mechanism of the redox-driven proton pumping, we investigated the kinetics of electron and proton transfer in a structural variant of the ba3 oxidase where a putative "pump site" was modified by replacement of Asp372 by Ile. In this structural variant, proton pumping was uncoupled from internal electron transfer and O2 reduction. The results from our studies show that proton uptake to the pump site (time constant ∼65 μs in the wild-type cytochrome c oxidase) was impaired in the Asp372Ile variant. Furthermore, a reaction step that in the wild-type cytochrome c oxidase is linked to simultaneous proton uptake and release with a time constant of ∼1.2 ms was slowed to ∼8.4 ms, and in Asp372Ile was only associated with proton uptake to the catalytic site. These data identify reaction steps that are associated with protonation and deprotonation of the pump site, and point to the area around Asp372 as the location of this site in the ba3 cytochrome c oxidase.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

von Ballmoos, Christoph

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0027-8424

Publisher:

National Academy of Sciences NAS

Language:

English

Submitter:

Christoph von Ballmoos

Date Deposited:

08 Apr 2015 09:54

Last Modified:

19 Sep 2015 02:30

Publisher DOI:

10.1073/pnas.1422434112

BORIS DOI:

10.7892/boris.65883

URI:

https://boris.unibe.ch/id/eprint/65883

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