+ Site Statistics
References:
54,258,434
Abstracts:
29,560,870
PMIDs:
28,072,757
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Proton pumping by an inactive structural variant of cytochrome c oxidase



Proton pumping by an inactive structural variant of cytochrome c oxidase



Journal of Inorganic Biochemistry 140: 6-11



The aa3-type cytochrome c oxidases (CytcOs) from e.g. Rhodobacter sphaeroides and Paracoccus denitrificans harbor two proton-transfer pathways. The K pathway is used for proton uptake upon reduction of the CytcO, while the D pathway is used after binding of O2 to the catalytic site. The aim of the present study was to determine whether or not CytcO in which the K pathway is blocked (by e.g. the Lys362Met replacement) is capable of pumping protons. The process can not be studied using conventional assays because the O2-reduction activity is too low when the K pathway is blocked. Consequently, proton pumping with a blocked K pathway has not been demonstrated directly. Here, the Lys362Met and Ser299Glu structural variants were reconstituted in liposomes and allowed to (slowly) become completely reduced. Then, the reaction with O2 was studied with μs time resolution after flash photolysis of a blocking CO ligand bound to heme a3. The data show that with both the inactive Lys362Met and partly active Ser299Glu variants proton release occurred with the same time constants as with the wild-type oxidase, i.e. ~200μs and ~3ms, corresponding in time to formation of the ferryl and oxidized states, respectively. Thus, the data show that the K pathway is not required for proton pumping, suggesting that D and K pathways operate independently of each other after binding of O2 to the catalytic site.

(PDF emailed within 0-6 h: $19.90)

Accession: 055260425

Download citation: RISBibTeXText

PMID: 25042731

DOI: 10.1016/j.jinorgbio.2014.06.016


Related references

Variable proton-pumping stoichiometry in structural variants of cytochrome c oxidase. Biochimica et Biophysica Acta 1797(6-7): 710-723, 2011

Impaired proton pumping in cytochrome c oxidase upon structural alteration of the D pathway. Biochimica et Biophysica Acta 1777(7-8): 897-903, 2008

Redesign of the proton-pumping machinery of cytochrome c oxidase: proton pumping does not require Glu(I-286). Biochemistry 39(51): 15847-15850, 2000

Alternative hypotheses of proton ejection in cytochrome oxidase vesicles. Transmembrane proton pumping or redox-linked deprotonation of phospholipid-cytochrome c complex(es). Febs Letters 151(2): 167-178, 1983

Proton pumping in cytochrome c oxidase: energetic requirements and the role of two proton channels. Biochimica et Biophysica Acta 1837(7): 1165-1177, 2014

Proton pumping in cytochrome c oxidase: the coupling between proton and electron gating. Proceedings of the National Academy of Sciences of the United States of America 107(19): 8505-8506, 2010

The identity of the transient proton loading site of the proton-pumping mechanism of cytochrome c oxidase. Biochimica et Biophysica Acta 1807(1): 80-84, 2011

Proton-coupled electron transfer and the role of water molecules in proton pumping by cytochrome c oxidase. Proceedings of the National Academy of Sciences of the United States of America 112(7): 2040-2045, 2015

From indophenol oxidase and atmungsferment to proton pumping cytochrome oxidase aa 3 copper zinc manganate. Chemica Scripta 28A: 35-40, 1988

Proton pumping and oxidase activity of thermophilic cytochrome oxidase remain after its extensive proteolysis. Biochemical and Biophysical Research Communications 113(2): 575-580, 1983

The cbb3-type cytochrome c oxidase from Rhodobacter sphaeroides, a proton-pumping heme-copper oxidase. Biochimica et Biophysica Acta 1365(3): 421-434, July 20, 1998

Internal charge transfer in cytochrome c oxidase at a limited proton supply: proton pumping ceases at high pH. Biochimica et Biophysica Acta 1790(6): 552-557, 2009

The functional catalytic unit involved in proton pumping by rat liver cytochrome-c reductase and by cytochrome-c oxidase. Biochimica et Biophysica Acta 973(1): 29-34, 1989

Cytochrome c oxidase depleted of subunit III: proton-pumping, respiratory control, and pH dependence of the midpoint potential of cytochrome a. Journal of Inorganic Biochemistry 23(3-4): 357-364, 1985

A quantum chemical study of the mechanism for proton-coupled electron transfer leading to proton pumping in cytochrome c oxidase. Molecular Physics 108(19-20): 2733-2743, 2010