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Chaperones of F1-ATPase.

Ludlam A, Brunzelle J, Pribyl T, Xu X, Gatti DL, Ackerman SH - J. Biol. Chem. (2009)

Bottom Line: One important feature of this model was the prediction that as long as Atp11p is bound to beta and Atp12p is bound to alpha, the two F(1) subunits cannot interact at either the catalytic site or the noncatalytic site interface.Here we present the structures of Atp11p from Candida glabrata and Atp12p from Paracoccus denitrificans, and we show that some features of the Wang model are correct, namely that binding of the chaperones to alpha and beta prevents further interactions between these F(1) subunits.However, Atp11p and Atp12p do not resemble alpha or beta, and it is instead the F(1) gamma subunit that initiates the release of the chaperones from alpha and beta and their further assembly into the mature complex.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

ABSTRACT
Mitochondrial F(1)-ATPase contains a hexamer of alternating alpha and beta subunits. The assembly of this structure requires two specialized chaperones, Atp11p and Atp12p, that bind transiently to beta and alpha. In the absence of Atp11p and Atp12p, the hexamer is not formed, and alpha and beta precipitate as large insoluble aggregates. An early model for the mechanism of chaperone-mediated F(1) assembly (Wang, Z. G., Sheluho, D., Gatti, D. L., and Ackerman, S. H. (2000) EMBO J. 19, 1486-1493) hypothesized that the chaperones themselves look very much like the alpha and beta subunits, and proposed an exchange of Atp11p for alpha and of Atp12p for beta; the driving force for the exchange was expected to be a higher affinity of alpha and beta for each other than for the respective chaperone partners. One important feature of this model was the prediction that as long as Atp11p is bound to beta and Atp12p is bound to alpha, the two F(1) subunits cannot interact at either the catalytic site or the noncatalytic site interface. Here we present the structures of Atp11p from Candida glabrata and Atp12p from Paracoccus denitrificans, and we show that some features of the Wang model are correct, namely that binding of the chaperones to alpha and beta prevents further interactions between these F(1) subunits. However, Atp11p and Atp12p do not resemble alpha or beta, and it is instead the F(1) gamma subunit that initiates the release of the chaperones from alpha and beta and their further assembly into the mature complex.

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Details of the Atp12p structure. A, stereo view of the C-domain (from the top) showing a central helix surrounded by six other helices. B, relative motions of Atp12p N- and C-domains. Stereo view of four different structures of wild type Atp12p (shown as red, blue, yellow, and green ribbons) and of D202K Atp12p (shown as a cyan ribbon) superimposed through their N-domains to highlight the relative motion of the C-domain. C, detail of the 1.0 Å structure of wild type Atp12p around Asp-202 (visible in two conformations). D, detail of the 1.8 Å structure of D202K Atp12p around Lys-202. /2Fo − Fc/ σA maps are contoured at 1σ.
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Figure 4: Details of the Atp12p structure. A, stereo view of the C-domain (from the top) showing a central helix surrounded by six other helices. B, relative motions of Atp12p N- and C-domains. Stereo view of four different structures of wild type Atp12p (shown as red, blue, yellow, and green ribbons) and of D202K Atp12p (shown as a cyan ribbon) superimposed through their N-domains to highlight the relative motion of the C-domain. C, detail of the 1.0 Å structure of wild type Atp12p around Asp-202 (visible in two conformations). D, detail of the 1.8 Å structure of D202K Atp12p around Lys-202. /2Fo − Fc/ σA maps are contoured at 1σ.

Mentions: A protein from Agrobacterium tumefaciens (PDB code 2R6I) very similar to P. denitrificans Atp12p was identified by the Midwest Center for Structural Genomics but was not characterized. Based on our study, 2R6I can now be assigned as the Atp12p chaperone of that bacterium. A structural homology search of Atp12p against the entire PDB bank identified at low threshold 2 additional neighbors for the N-domain and 67 additional neighbors for the C-domain; superposition of the best scoring neighbors onto each domain of Atp12p did not reveal a level of similarity sufficient to draw mechanistic information from the search. However, it is of interest that the core of the C-domain consists of a central helix surrounded by six other helices (Fig. 4A). This topology is reminiscent of the fold of the membrane domains of colicins, pore-forming toxins, and Bcl-2 apoptotic proteins, all of which are thought to become variably associated with biological membranes upon some conformational change (30–32). Despite this similarity, there is no evidence at this time that in vivo Atp12p might be associated with the mitochondrial inner membrane or the bacterial cell membrane.


Chaperones of F1-ATPase.

Ludlam A, Brunzelle J, Pribyl T, Xu X, Gatti DL, Ackerman SH - J. Biol. Chem. (2009)

Details of the Atp12p structure. A, stereo view of the C-domain (from the top) showing a central helix surrounded by six other helices. B, relative motions of Atp12p N- and C-domains. Stereo view of four different structures of wild type Atp12p (shown as red, blue, yellow, and green ribbons) and of D202K Atp12p (shown as a cyan ribbon) superimposed through their N-domains to highlight the relative motion of the C-domain. C, detail of the 1.0 Å structure of wild type Atp12p around Asp-202 (visible in two conformations). D, detail of the 1.8 Å structure of D202K Atp12p around Lys-202. /2Fo − Fc/ σA maps are contoured at 1σ.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719352&req=5

Figure 4: Details of the Atp12p structure. A, stereo view of the C-domain (from the top) showing a central helix surrounded by six other helices. B, relative motions of Atp12p N- and C-domains. Stereo view of four different structures of wild type Atp12p (shown as red, blue, yellow, and green ribbons) and of D202K Atp12p (shown as a cyan ribbon) superimposed through their N-domains to highlight the relative motion of the C-domain. C, detail of the 1.0 Å structure of wild type Atp12p around Asp-202 (visible in two conformations). D, detail of the 1.8 Å structure of D202K Atp12p around Lys-202. /2Fo − Fc/ σA maps are contoured at 1σ.
Mentions: A protein from Agrobacterium tumefaciens (PDB code 2R6I) very similar to P. denitrificans Atp12p was identified by the Midwest Center for Structural Genomics but was not characterized. Based on our study, 2R6I can now be assigned as the Atp12p chaperone of that bacterium. A structural homology search of Atp12p against the entire PDB bank identified at low threshold 2 additional neighbors for the N-domain and 67 additional neighbors for the C-domain; superposition of the best scoring neighbors onto each domain of Atp12p did not reveal a level of similarity sufficient to draw mechanistic information from the search. However, it is of interest that the core of the C-domain consists of a central helix surrounded by six other helices (Fig. 4A). This topology is reminiscent of the fold of the membrane domains of colicins, pore-forming toxins, and Bcl-2 apoptotic proteins, all of which are thought to become variably associated with biological membranes upon some conformational change (30–32). Despite this similarity, there is no evidence at this time that in vivo Atp12p might be associated with the mitochondrial inner membrane or the bacterial cell membrane.

Bottom Line: One important feature of this model was the prediction that as long as Atp11p is bound to beta and Atp12p is bound to alpha, the two F(1) subunits cannot interact at either the catalytic site or the noncatalytic site interface.Here we present the structures of Atp11p from Candida glabrata and Atp12p from Paracoccus denitrificans, and we show that some features of the Wang model are correct, namely that binding of the chaperones to alpha and beta prevents further interactions between these F(1) subunits.However, Atp11p and Atp12p do not resemble alpha or beta, and it is instead the F(1) gamma subunit that initiates the release of the chaperones from alpha and beta and their further assembly into the mature complex.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

ABSTRACT
Mitochondrial F(1)-ATPase contains a hexamer of alternating alpha and beta subunits. The assembly of this structure requires two specialized chaperones, Atp11p and Atp12p, that bind transiently to beta and alpha. In the absence of Atp11p and Atp12p, the hexamer is not formed, and alpha and beta precipitate as large insoluble aggregates. An early model for the mechanism of chaperone-mediated F(1) assembly (Wang, Z. G., Sheluho, D., Gatti, D. L., and Ackerman, S. H. (2000) EMBO J. 19, 1486-1493) hypothesized that the chaperones themselves look very much like the alpha and beta subunits, and proposed an exchange of Atp11p for alpha and of Atp12p for beta; the driving force for the exchange was expected to be a higher affinity of alpha and beta for each other than for the respective chaperone partners. One important feature of this model was the prediction that as long as Atp11p is bound to beta and Atp12p is bound to alpha, the two F(1) subunits cannot interact at either the catalytic site or the noncatalytic site interface. Here we present the structures of Atp11p from Candida glabrata and Atp12p from Paracoccus denitrificans, and we show that some features of the Wang model are correct, namely that binding of the chaperones to alpha and beta prevents further interactions between these F(1) subunits. However, Atp11p and Atp12p do not resemble alpha or beta, and it is instead the F(1) gamma subunit that initiates the release of the chaperones from alpha and beta and their further assembly into the mature complex.

Show MeSH
Related in: MedlinePlus