Formation of the b subunit dimer is necessary for interaction with F1- ATPase

Paul L. Sorgen, Michael R. Bubb, Kimberly A. McCormick, Arthur S. Edison, Brian D. Cain

Research output: Contribution to journalArticle

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Abstract

In earlier work, we [McCormick, K. A., et al. (1993) J. Biol. Chem. 268, 24683-24691] observed that mutations at Ala-79 of the b subunit affect assembly of F1F0 ATP synthase. Polypeptides modeled on the soluble portion of the b subunit (b(sol)) with substitutions at the position corresponding to Ala-79 have been used to investigate secondary structure and dimerization of the b subunit. Circular dichroism spectra and chymotrypsin digestion experiments suggested that the recombinant polypeptides with Ala-79 substitutions assumed conformations similar to the b(sol) polypeptide. However, cross-linking studies of the Ala-79 substitution b(sol) polypeptides revealed defects in dimerization. The efficiency of dimer formation appeared to be related to the capacity of the altered b(sol) polypeptides for competing with F1-ATPase for binding to F1-depleted membrane vesicles. Ala- 79 substitution polypeptides displaying limited dimerization, such as b(sol) (Ala-79→Leu), were shown to elute with F1-ATPase during size exclusion chromatography, suggesting a specific interaction. Sedimentation equilibrium studies indicated that 8% of the b(sol) (Ala-79→Leu) polypeptide was in the form of a 30.6 kDa dimer and 92% a 15.3 kDa monomer. When the dimer concentration of b(sol) (Ala-79-Leu) was normalized to the concentration of b(sol), both had virtually identical capacities for competing with F1- depleted membrane vesicles for binding F1-ATPase. The result indicated that the amount of dimer formed is directly proportional to its ability to bind F1-ATPase. This suggests that formation of the b subunit dimer may be a necessary step preceding F1-ATPase binding in the assembly of the enzyme complex.

Original languageEnglish (US)
Pages (from-to)923-932
Number of pages10
JournalBiochemistry
Volume37
Issue number3
DOIs
StatePublished - Jan 20 1998

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Proton-Translocating ATPases
Polymethyl Methacrylate
Dimers
Peptides
Dimerization
Substitution reactions
Membranes
Size exclusion chromatography
Chymotrypsin
Circular Dichroism
Sedimentation
Gel Chromatography
Conformations
Digestion
Monomers
Defects
Mutation
Enzymes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Sorgen, P. L., Bubb, M. R., McCormick, K. A., Edison, A. S., & Cain, B. D. (1998). Formation of the b subunit dimer is necessary for interaction with F1- ATPase. Biochemistry, 37(3), 923-932. https://doi.org/10.1021/bi972309+

Formation of the b subunit dimer is necessary for interaction with F1- ATPase. / Sorgen, Paul L.; Bubb, Michael R.; McCormick, Kimberly A.; Edison, Arthur S.; Cain, Brian D.

In: Biochemistry, Vol. 37, No. 3, 20.01.1998, p. 923-932.

Research output: Contribution to journalArticle

Sorgen, PL, Bubb, MR, McCormick, KA, Edison, AS & Cain, BD 1998, 'Formation of the b subunit dimer is necessary for interaction with F1- ATPase', Biochemistry, vol. 37, no. 3, pp. 923-932. https://doi.org/10.1021/bi972309+
Sorgen, Paul L. ; Bubb, Michael R. ; McCormick, Kimberly A. ; Edison, Arthur S. ; Cain, Brian D. / Formation of the b subunit dimer is necessary for interaction with F1- ATPase. In: Biochemistry. 1998 ; Vol. 37, No. 3. pp. 923-932.
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