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J Bacteriol, July 1998, p. 3663-3670, Vol. 180, No. 14
National Institute of Genetics,
Received 29 December 1997/Accepted 28 April 1998
The ftsE(Ts) mutation of Escherichia coli
causes defects in cell division and cell growth. We expressed alkaline
phosphatase (PhoA) fusion proteins of KdpA, Kup, and TrkH, all of which
proved functional in vivo as K+ ion pumps, in the mutant
cells. During growth at 41°C, these proteins were progressively lost
from the membrane fraction. The reduction in the abundance of these
proteins inversely correlated with cell growth, but the preformed
proteins in the membrane were stable at 41°C, indicating that the
molecules synthesized at the permissive temperature were diluted in a
growth-dependent manner at a high temperature. Pulse-chase experiments
showed that KdpA-PhoA was synthesized, but the synthesized protein did
not translocate into the membrane of the ftsE(Ts) cells at 41°C and
degraded very rapidly. The loss of KdpA-PhoA from the membrane
fractions of ftsE(Ts) cells was suppressed by a multicopy plasmid
carrying the ftsE+ gene. While cell growth
stopped when the abundance of these proteins decreased 15-fold, the
addition of a high concentration of K+ ions specifically
alleviated the growth defect of ftsE(Ts) cells but not cell division,
and the cells elongated more than 100-fold. We conclude that one of the
causes of growth cessation in the ftsE(Ts) mutants is a defect in
the translocation of K+-pump proteins into the cytoplasmic
membrane.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
ftsE(Ts) Affects Translocation of
K+-Pump Proteins into the Cytoplasmic Membrane of
Escherichia coli
*
Corresponding author. Mailing address: National
Institute of Genetics, Mishima, Shizuoka-ken 411, Japan. Phone: 81 559 81 6827. Fax: 81 559 81 6826. E-mail:
anishimu{at}lab.nig.ac.jp.
J Bacteriol, July 1998, p. 3663-3670, Vol. 180, No. 14
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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