| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Bacteria like Escherichia coli are known to die more than 90% at the early stationary phase when grown in rich medium. Author has been isolated a mutant strain, which prompts dead cells to lyse, in the study on the mechanism of cell death. Analysis of the mutant revealed that the lysis is proceeded by unknown of σE regulon. This study aimed to decipher the molecular mechanisms of cell death and dead cell lysis in the stationary phase, and was performed by analyses of the conditions inducing cell death andσE of regulon.
1) Several experiments revealed that cell death was induced by nitrogen starvation, which suggested existence of cascade to cell. A condition to induce cell death in synthetic medium has thus been established. Changes in expression of genomic genes under the condition established were analyzed by DNA microarray, which showed that several hundred genes includingσS andσH regulons were significantly altered in expression. 2) σE regulon related to lysis specific for dead cells was searched. Altered proteins under the dead-cell lysis condition were analyzed by two-dimensional gel electrophoresis followed by TOF-MASS. As a result, 9 proteins including knownσE regulon proteins were identified, but these proteins were not directly related to dead cell lysis, which was shown by gene disruption experiments. 3) A transient expression system ofσE was constructed, which indicated thatσE regulon is directly involved in dead cell lysis. 4) Using the transient system, alteration in expression of genomic genes after 1-h induction ofσE expression was analyzed by DNA microarray, and up- regulated 130 genes and down-regulated 49 genes were identified. 5) A condition that directs from cell death to dead cell lysis under nitrogen starvation andσE expression has been established.
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