A redox switch shapes the Lon protease exit pore to facultatively regulate proteolysis.
The Lon AAA+ protease degrades damaged or misfolded proteins in its intramolecular chamber. Its activity must be precisely controlled, but the mechanism by which Lon is regulated in response to different environments is not known. Facultative anaerobes in the Enterobacteriaceae family, mostly symbionts and pathogens, encounter both anaerobic and aerobic environments inside and outside the host's body, respectively. The bacteria characteristically have two cysteine residues on the Lon protease (P) domain surface that unusually form a disulfide bond. Here we show that the cysteine residues act as a redox switch of Lon. Upon disulfide bond reduction, the exit pore of the P-domain ring narrows by ∼30%, thus interrupting product passage and decreasing activity by 80%; disulfide bonding by oxidation restores the pore size and activity. The redox switch (E°' = -227 mV) is appropriately tuned to respond to variation between anaerobic and aerobic conditions, thus optimizing the cellular proteolysis level for each environment.
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] RIKEN Structural Biology Laboratory, Yokohama, Japan.
Wataru
W
Nishii
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, Yokohama, Japan.
Mutsuko
M
Kukimoto-Niino
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] RIKEN Structural Biology Laboratory, Yokohama, Japan.
Takaho
T
Terada
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, Yokohama, Japan.
Mikako
M
Shirouzu
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] RIKEN Structural Biology Laboratory, Yokohama, Japan.
Tomonari
T
Muramatsu
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
Masaki
M
Kojima
Himeji Hinomoto College, Hyogo, Japan.
Hiroshi
H
Kihara
1] RIKEN Systems and Structural Biology Center, Yokohama, Japan. [2] RIKEN Structural Biology Laboratory, Yokohama, Japan.
Shigeyuki
S
Yokoyama
D000332:Aerobiosis; D000693:Anaerobiosis; D003545:Cysteine / Q000378:metabolism; D004755:Enterobacteriaceae / Q000201:enzymology; D004777:Environment; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010957:Plasmids / Q000235:genetics; D049070:Protease La / Q000378:metabolism*; D011487:Protein Conformation; D059748:Proteolysis
D049070:Protease La; D003545:Cysteine