The role of the amino-terminal beta-barrel domain of the alpha and beta subunits in the yeast F1-ATPase.
The crystal structure of mitochondrial F1-ATPase indicates that the alpha and beta subunits fold into a structure defined by three domains: the top beta-barrel domain, the middle nucleotide-binding domain, and the C-terminal alpha-helix bundle domain (Abrahams et al., 1994); Bianchet et al., 1998). The beta-barrel domains of the alpha and beta subunits form a crown structure at the top of F1, which was suggested to stabilize it (Abrahams et al. 1994). In this study, the role of the beta-barrel domain in the alpha and beta subunits of the yeast Saccharomyces cerevisiae F1, with regard to its folding and assembly, was investigated. The beta-barrel domains of yeast F1alpha and beta subunits were expressed individually and together in Escherichia coli. When expressed separately, the beta-barrel domain of the beta subunit formed a large aggregate structure, while the domain of the alpha subunit was predominately a monomer or dimer. However, coexpression of the beta-barrel domain of alpha subunit with the beta-barrel domain of beta subunit, greatly reduced the aggregation of the beta subunit domain. Furthermore, the two domains copurified in complexes with the major portion of the complex found in a small molecular weight form. These results indicate that the beta-barrel domain of the alpha and beta subunits interact specifically with each other and that these interactions prevent the aggregation of the beta-barrel domain of the beta subunit. These results mimic in vivo results and suggest that the interactions of the beta-barrel domains may be critical during the folding and assembly of F1.
Yao
B
B
Department of Biochemistry and Molecular Biology, The Chicago Medical School, Illinois 60064, USA.
Mueller
D M
DM
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003001:Cloning, Molecular; D004926:Escherichia coli; D046911:Macromolecular Substances; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D046911:Macromolecular Substances; D010446:Peptide Fragments; D011994:Recombinant Proteins; D006180:Proton-Translocating ATPases