This Article Full Text Full Text (PDF) Other Versions of this Article: JB.00191-07v1 189/15/5463    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Claggett, S. B. Articles by Cain, B. D. Search for Related Content PubMed PubMed Citation Articles by Claggett, S. B. Articles by Cain, B. D.

Functional Incorporation of Chimeric b Subunits into F₁F_o ATP Synthase

Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32605,¹ Department of Biochemistry, University of Western Ontario, London, Ontario, Canada N6A 5C1²

Received 5 February 2007/ Accepted 15 May 2007

F₁F_o ATP synthases function by a rotary mechanism. The enzyme's peripheral stalk serves as the stator that holds the F₁ sector and its catalytic sites against the movement of the rotor. In Escherichia coli, the peripheral stalk is a homodimer of identical b subunits, but photosynthetic bacteria have open reading frames for two different b-like subunits thought to form heterodimeric b/b' peripheral stalks. Chimeric b subunit genes have been constructed by substituting sequence from the Thermosynechococcus elongatus b and b' genes in the E. coli uncF gene, encoding the b subunit. The recombinant genes were expressed alone and in combination in the E. coli deletion strain KM2 (b). Although not all of the chimeric subunits were incorporated into F₁F_o ATP synthase complexes, plasmids expressing either chimeric b_E39-I86 or b'_E39-I86 were capable of functionally complementing strain KM2 (b). Strains expressing these subunits grew better than cells with smaller chimeric segments, such as those expressing the b'_E39-D53 or b_L54-I86 subunit, indicating intragenic suppression. In general, the chimeric subunits modeled on the T. elongatus b subunit proved to be more stable than the b' subunit in vitro. Coexpression of the b_E39-I86 and b'_E39-I86 subunits in strain KM2 (b) yielded F₁F_o complexes containing heterodimeric peripheral stalks composed of both subunits.

Published ahead of print on 25 May 2007.

This article has been cited by other articles:

• Wood, K. S., Dunn, S. D. (2007). Role of the Asymmetry of the Homodimeric b2 Stator Stalk in the Interaction with the F1 Sector of Escherichia coli ATP Synthase. J. Biol. Chem. 282: 31920-31927 [Abstract] [Full Text]