Stabilization of FtsH-unfolded protein complex by binding of ATP and blocking of protease.
The function of an ATP-dependent membrane protease FtsH was investigated using the enzyme from Thermus thermophilus HB8. An FtsH mutant with replacement of Glu-419 in the zinc-binding motif by Cys lost the activity to digest casein, a model unfolded protein, and the small ATPase activity of this mutant was no longer stimulated by casein. In the presence of ATP or ATPgammaS, but not ADP, a mutant FtsH-unfolded protein complex was isolated, indicating that ATP binding, but not ATP hydrolysis, is required for FtsH to form a stable complex with an unfolded protein. The FtsH without mutation at Glu-419 did not produce a stable complex with casein in the presence of any nucleotides tested and therefore it appears that blocking proteolysis also contributes to stabilization of the complex.
Makyio
Hisayoshi
H
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, 226-8503, Yokohama, Japan.
Niwa
Hajime
H
Motohashi
Ken
K
Taguchi
Hideki
H
Yoshida
Masasuke
M
D000255:Adenosine Triphosphate / Q000378:metabolism*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D017931:DNA Primers; D004795:Enzyme Stability; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D016963:Thermus thermophilus / Q000201:enzymology
D001426:Bacterial Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D003545:Cysteine