S. Asoh et al., A TRACE AMOUNT OF THE HUMAN PRO-APOPTOTIC FACTOR BAX INDUCES BACTERIAL DEATH ACCOMPANIED BY DAMAGE OF DNA, The Journal of biological chemistry, 273(18), 1998, pp. 11384-11391
An amount of human pro-apoptotic Bar as low as 0.01% of total protein
was sufficient to cause cell death in Escherichia coli. The bacterial
cell death was examined using a viable bacteria-specific fluorescence
indicator system and loss of colony formation ability. Coexpression of
anti-apoptotic Bcl-x(L) showed a modest inhibitory effect on the cell
death caused by Bar. The trace amount of Bay elongated E. coli and ac
cumulated monounsaturated fatty acids, suggesting an unusual metabolis
m of redox in the host. In fact, an increase of KCN-dependent O-2 cons
umption accompanied the expression of Bar. At the same time, a fluores
cent pH indicator showed the apparent accumulation of protons outside
the cell, suggesting that the membrane is intact. Bax increased the le
vel of superoxide anion as measured by the expression of superoxide-de
pendent promoter. Nicked DNA was significantly generated, and the freq
uency of mutations resistant to rifampicin was increased by 30-fold, d
epending upon the expression of Bar. It is proposed that trace amounts
of Bar increase oxygen consumption, triggering generation of superoxi
de, which affects DNA, leading to bacterial death.