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- Title
<f>pK<sub>a</sub></f> of the essential Glu54 and backbone conformation for subunit <f>c</f> from the H<sup>+</sup>-coupled F<sub>1</sub>F<sub>0</sub> ATP synthase from an alkaliphilic Bacillus
- Authors
Rivera-Torres, Iván O.; Krueger-Koplin, Ray D.; Hicks, David B.; Cahill, Sean M.; Krulwich, Terry A.; Girvin, Mark E.
- Abstract
The conformation of the ATP synthase <f>c</f>-subunit and the <f>pKa</f> of its essential E54 residue were characterized in alkaliphilic Bacillus pseudofirmus OF4. The <f>c</f>-subunit folds as a helix–loop–helix, with inter-helical contacts demonstrated by paramagnetic relaxation effects. The E54 <f>pKa</f> of 7.7 is significantly higher than in non-alkaliphiles, which likely prevents proton loss from the <f>c</f>-rotor at high pH. The E54 <f>pKa</f> was unchanged in a mutant, <f>c</f>P51A, that has a severe ATP synthesis defect at high pH only. <f>c</f>P51 must have some structural role that accounts for the mutant defect, such as different subunit-subunit interactions at high pH.
- Subjects
GENETIC mutation; PROTONS; ATOMS; PROTEINS
- Publication
FEBS Letters, 2004, Vol 575, Issue 1-3, p131
- ISSN
0014-5793
- Publication type
Article
- DOI
10.1016/j.febslet.2004.08.049