Reactivation of the chloroplast CF1-ATPase β subunit by trace amounts of the CF1 α subunit suggests a chaperonin-like activity for CF(1α)

A. Avni, S. Avital, Z. Gromet-Elhanan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Incubation of tobacco and lettuce thylakoids with 2 M LiCl in the presence of MgATP removes the β subunit from their CF1-ATPase (CF1β) together with varying amounts of the CF1 α subunit (CF1α). These 2 M LiCl extracts, as with the one obtained from spinach thylakoids (Avital, S., and Gromet-Elhanan, Z. (1991) J. Biol. Chem. 266, 7067-7072), could form active hybrid ATPases when reconstituted into inactive β-less Rhodospirillum rubrum chromatophores. Pure CF1β fractions that have been isolated from these extracts could not form such active hybrids by themselves, but could do so when supplemented with trace amounts (less than 5%) of CF1α. A mitochondrial F1-ATPase α subunit was recently reported to be a heat-shock protein, having two amino acid sequences that show a highly conserved identity with sequences found in molecular chaperones (Luis, A.M., Alconada, A., and Cuezva, J.M. (1990) J. Biol. Chem. 265, 7713-7716). These sequences are also conserved in CF1α isolated from various plants, but not in F1β subunits. The above described reactivation of CF1β by trace amounts of CF1α could thus be due to a chaperonin-like function of CF1α, which involves the correct, active folding of isolated pure CF1β.

Original languageEnglish
Pages (from-to)7317-7320
Number of pages4
JournalJournal of Biological Chemistry
Volume266
Issue number12
StatePublished - 1991
Externally publishedYes

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