pKaof the essential Glu54 and backbone conformation for subunitcfrom the H+-coupled F1F0ATP synthase from an alkaliphilicBacillus
- 11 September 2004
- journal article
- Published by Wiley in FEBS Letters
- Vol. 575 (1-3) , 131-135
- https://doi.org/10.1016/j.febslet.2004.08.049
Abstract
The conformation of the ATP synthase c-subunit and the pKa of its essential E54 residue were characterized in alkaliphilic Bacillus pseudofirmus OF4. The c-subunit folds as a helix–loop–helix, with inter-helical contacts demonstrated by paramagnetic relaxation effects. The E54 pKa of 7.7 is significantly higher than in non-alkaliphiles, which likely prevents proton loss from the c-rotor at high pH. The E54 pKa was unchanged in a mutant, cP51A, that has a severe ATP synthesis defect at high pH only. cP51 must have some structural role that accounts for the mutant defect, such as different subunit-subunit interactions at high pHKeywords
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