1992 Fiscal Year Final Research Report Summary
Analysis of the mechanism of the invasion of the A subunit of heat-labile enterotoxin from enterotoxigenic E coli
| Project/Area Number |
03670225
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
細菌学
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| Research Institution | Fujita Health University |
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Principal Investigator |
TSUJI Takao Fujita Health Univ., Medicine, Associate Professor, 医学部, 助教授 (60171998)
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| Project Period (FY) |
1991 – 1992
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| Keywords | enterotoxigenic / Escherichia coli / heat-labile-enterotoxin / nick / ADP-ribosylation / site direct mutagenesis / alosteric effect |
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| Research Abstract |
In this time, we can get the data as followed ;
1. Vibrio cholerae produced the protease(this is named as VC-1) that could nick at the position 192(Arg) from the N-terminus of the A subunit of unnicked heat-labile enterotoxins from enterotoxigenic Escherichia coli.
2. The Chinese hamster overly cell, which is elongated with the addition of toxin to its culture medium, produced the protease that could nick the unnicked heat-labile enterotoxin A subunit.
3. THE free A subunit, which did not bind to B subunit, was detected in the cell extract from enterotoxigenic E.coli and was purified. It was very unstable and its biological activity was lower than that of the normal A subunit.
4. There was the heterogeneity among the heat-labile enterotoxins(LTp) purified from the porcine enterotoxigenic E.coli strains. 5. The amino acid substitution at the position 112 of the A subunit from Glu to Lys(E112X) affects the ADP-ribosyltransferase activity of its A1 flagment. Therefore it is suggested that Glu 112 is important for the its ADP-ribosyltransferase activity.
6. Though the E112X mutant LT did not have ADP-ribosyltransferase activity, it had the inhibition activity of the interaction between ADP ribosylation factor(ARF) to cholera toxin. These data indicates that the ARF could activate the cholera toxin with the alosteric effect.
7. My coworker, Dr.Shida, found that there were two kinds of the glycoprotein, which could react with LT, in heated cow milk, but not in unheated one. By amino acid analyze of them, they were alpha-lactoalbumin and beta-lactoglobulin.
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