Properties of a revertant of Escherichia coli viable in the presence of spermidine accumulation: increase in L-glycerol 3-phosphate.
Escherichia coli CAG2242 cells are deficient in the speG gene encoding spermidine acetyltransferase. When these cells were cultured in the presence of 0.5 to 4 mM spermidine, their viability was greatly decreased through the inhibition of protein synthesis by overaccumulation of spermidine. When the cells were cultured with a high concentration of spermidine (4 mM), a revertant strain was obtained. We found that a 55-kDa protein, glycerol kinase, was overexpressed in the revertant and that synthesis of a ribosome modulation factor and the RNA polymerase sigma(38) subunit, factors important for cell viability, was increased in the revertant. Levels of L-glycerol 3-phosphate also increased in the revertant. Transformation of glpFK, which encodes a glycerol diffusion facilitator (glpF) and glycerol kinase (glpK), to E. coli CAG2242 partially prevented the cell death caused by accumulation of spermidine. It was also found that L-glycerol 3-phosphate inhibited spermidine binding to ribosomes and attenuated the inhibition of protein synthesis caused by high concentrations of spermidine. These results indicate that L-glycerol 3-phosphate reduces the binding of excess amounts of spermidine to ribosomes so that protein synthesis is recovered.
Raj
V S
VS
Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Tomitori
H
H
Yoshida
M
M
Apirakaramwong
A
A
Kashiwagi
K
K
Takio
K
K
Ishihama
A
A
Igarashi
K
K
D000595:Amino Acid Sequence; D020346:Aquaporins; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005991:Glycerol Kinase / Q000235:genetics / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon; D013095:Spermidine / Q000378:metabolism* / Q000494:pharmacology
D020346:Aquaporins; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D005994:Glycerophosphates; C078043:GlpF protein, E coli; C029620:alpha-glycerophosphoric acid; D005991:Glycerol Kinase; D013095:Spermidine