Nuclear localization of bacterial Streptoalloteichus hindustanus bleomycin resistance protein in mammalian cells.
Prokaryotes produce a variety of toxins that affect genomic function of both eukaryotes and prokaryotes. The 375-base pair bacterial gene Streptoalloteichus hindustanus (Sh) ble encodes a small protein, Streptoalloteichus hindustanus bleomycin resistance protein (BRP), that inhibits in vitro DNA cleavage by the prokaryotic glycopeptide bleomycin, which is a clinically used anticancer drug. NIH/3T3 cells infected with a retroviral vector containing Sh ble (SH-9 cells) were highly resistant to the cytotoxicity of bleomycin-like drugs but not to the cytotoxicity of other, structurally unrelated, DNA-cleaving agents. Expression of BRP did not markedly alter total cellular content or distribution of bleomycin-like compounds. Fluorescently labeled bleomycin was primarily localized in cytoplasmic vesicles in NIH/3T3 and SH-9 cells, whereas BRP, which has no established nuclear localization sequence, was segregated to the nucleus and more specifically to euchromatin. This karyophilic BRP may intercept bleomycin in the nucleus.
Calmels
T P
TP
Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania 15261.
Mistry
J S
JS
Watkins
S C
SC
Robbins
P D
PD
McGuire
R
R
Lazo
J S
JS
D016475:3T3 Cells; D000192:Actinomycetales / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001761:Bleomycin / Q000494:pharmacology*; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects; D004352:Drug Resistance, Microbial; D007150:Immunohistochemistry; D051379:Mice; D016253:Microscopy, Immunoelectron
D001426:Bacterial Proteins; D001761:Bleomycin