Tetracycline/H+ antiporter was degraded rapidly in Escherichia coli cells when truncated at last transmembrane helix and this degradation was protected by overproduced GroEL/ES.
The in vivo degradation of the plasmid-encoded tetracycline/H+ antiporter (TET) in Escherichia coli cells was studied using three mutants with carboxyl-terminal truncation at the positions in the hydrophilic carboxyl-terminal tail (TET388), in the last putative transmembrane helix XII (TET382), and immediately before the helix XII (TET365). All the mutant TET proteins were localized in the membrane. Expressed TET388 was active in transport and stable against proteolysis. However, TET382 and TET365 were inactive and proteolyzed rapidly. Thus, the importance of the helix XII for protease-resistant proper folding of TET is obvious. Interestingly, overproduced chaperonin (GroEL and GroES) partly prevented degradation of TET365.
Sato
K
K
Research Laboratory for Resources Utilization, Tokyo Institute of Technology, Yokohama, Japan.
Sato
M H
MH
Yamaguchi
A
A
Yoshida
M
M
D000595:Amino Acid Sequence; D017920:Antiporters / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D001483:Base Sequence; D018835:Chaperonin 10; D018834:Chaperonin 60; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000378:metabolism*; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D013752:Tetracycline / Q000378:metabolism
D017920:Antiporters; D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D017931:DNA Primers; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D013462:Sulfur Radioisotopes; C079051:tetA protein, Bacteria; D008715:Methionine; D013752:Tetracycline