Cleavage of colicin D is necessary for cell killing and requires the inner membrane peptidase LepB.
Colicin D is known to kill target cells by cleaving tRNA(Arg). A colicin D-resistant mutant was selected that was altered in the inner membrane leader peptidase, LepB. The substituted residue (Asn274Lys) is located close to the catalytic site. The mutation abolishes colicin D cleavage but not the processing of exported proteins. LepB is required for colicin D cleavage, releasing a small C-terminal fragment that retains full tRNase activity. The immunity protein was found to prevent colicin D processing and furthermore masks tRNase activity, thus protecting colicin D against LepB-mediated cleavage during export. Catalytic colicins share a consensus sequence at their putative processing site. Mutations affecting normal processing of colicin D abolish cytotoxicity without affecting the in vitro tRNase activity.
de Zamaroczy
M
M
Institut de Biologie Physico-Chimique, CNRS, UPR 9073, 75005, Paris, France. zamaroczy@ibpc.fr
Mora
L
L
Lecuyer
A
A
Géli
V
V
Buckingham
R H
RH
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D020134:Catalytic Domain; D003087:Colicins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D004926:Escherichia coli / Q000502:physiology; D005816:Genetic Complementation Test; D008565:Membrane Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D011709:Pyocins / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012260:Ribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
D001426:Bacterial Proteins; D003087:Colicins; D008565:Membrane Proteins; D011709:Pyocins; D012343:RNA, Transfer; D012260:Ribonucleases; D012697:Serine Endopeptidases; C026515:type I signal peptidase