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Bacterial cell death induced by human pro‐apoptotic Bax is blocked by an RNase E mutant that functions in an anti‐oxidant pathway
Author(s) -
NanbuWakao Rika,
Asoh Sadamitsu,
Nishimaki Kiyomi,
Tanaka Rie,
Ohta Shigeo
Publication year - 2000
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2000.00316.x
Subject(s) - biology , rnase p , paraquat , endoribonuclease , mutant , programmed cell death , apoptosis , microbiology and biotechnology , escherichia coli , gene , rna , biochemistry
Background Bax is a member of the Bcl‐2 family and induces apoptosis of mammalian cells. We have shown that a trace amount of human Bax induces the cell death of Escherichia coli , accompanied by damage to DNA, and that the region of Bax which is lethal to E. coli is also responsible for apoptosis‐inducing activity in the mammalian cells. Results We isolated a Bax‐resistant mutant from E. coli cells that survive in the presence of paraquat, a generator of superoxide, by screening a library constructed from the random insertion of a transposon. Psb1 (paraquat‐resistant, suppressor of Bax‐1) mutant had a Tn 10 transposon inserted in the rne gene of E. coli , splitting the RNase E gene ( rne ) into N‐ and C‐terminal halves. The introduction of the truncated 5′ end of rne specifically enhanced resistance to paraquat, prevented cell death induced by Bax and decreased the intracellular H 2 O 2 concentration. The region responsible for the paraquat‐ and Bax‐resistance was not the catalytic site for the endoribonuclease activity of RNase E. Conclusions The N‐terminal region of the RNase E protein inhibits bacterial death induced by human Bax as well as paraquat through a unique mechanism that is distinct from RNA digestion. This study implies that the protection of bacterial death induced by Bax is associated with an anti‐oxidant pathway and that a mutant RNase E has a novel function as an anti‐oxidant.