The product of uncI gene in F1Fo-ATP synthase operon plays a chaperone-like role to assist c-ring assembly.
Bacterial operons for F(1)F(o)-ATP synthase typically include an uncI gene that encodes a function-unknown small hydrophobic protein. When we expressed a hybrid F(1)F(o) (F(1) from thermophilic Bacillus PS3 and Na(+)-translocating F(o) from Propionigenium modestum) in Escherchia coli cells, we found that uncI derived from P. modestum was indispensable to produce active enzyme; without uncI, c-subunits in F(1)F(o) existed as monomers but not as functional c(11)-ring. When uncI was expressed from another plasmid at the same time, active F(1)F(o) with c(11)-ring was produced. A plasmid containing only uncI and c-subunit gene produced c(11)-ring, but a plasmid containing only c-subunit gene did not. Direct interaction of UncI protein with c-subunits was suggested from copurification of His-tagged UncI protein and c-subunits, both in the state of c(11)-ring and c-monomers. Na(+) induced dissociation of His-tagged UncI protein from c(11)-ring but not from c-monomers. These results show that UncI is a chaperone-like protein that assists c(11)-ring assembly from c-monomers in the membrane.
Suzuki
Toshiharu
T
ATP Synthesis Regulation Project, ICORP, Japan Science and Technology Corporation, Aomi 2-41, Tokyo 135-0064, Japan.
Ozaki
Yoko
Y
Sone
Nobuhito
N
Feniouk
Boris A
BA
Yoshida
Masasuke
M
D000255:Adenosine Triphosphate / Q000737:chemistry; D001407:Bacillus / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005822:Genetic Vectors; D007477:Ions / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism*; D009876:Operon; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics*; D011522:Protons; D012964:Sodium / Q000737:chemistry
D007477:Ions; D008565:Membrane Proteins; D018832:Molecular Chaperones; D011522:Protons; D000255:Adenosine Triphosphate; D012964:Sodium; D006180:Proton-Translocating ATPases