1998 Fiscal Year Final Research Report Summary
ENTEROTOXICITY OF HEAT-STABLE ENTEROTOXIN PRODUCED FROM ENTEROTOXIGENIC ESCHERICHIA COLI
| Project/Area Number |
09670289
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | NAGASAKI UNIVERSITY |
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Principal Investigator |
HIRAYAMA Toshiya NAGASAKI UNIVERSITY,INSTITUTE OF TROPICAL MEDICINE,PROFESSOR, 熱帯医学研究所, 教授 (50050696)
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| Co-Investigator(Kenkyū-buntansha) |
WADA Akihiro NAGASAKI UNIVERSITY,INSTITUTE OF TROPICAL MEDICINE,RESEARCH ASSOCIATE, 熱帯医学研究所, 助手 (70253698)
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| Project Period (FY) |
1997 – 1998
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| Keywords | ENTEROTOXITY / ENTEROTOXIGENIC ESCHERICHIA COLI / HEAT-STABEL ENTEROTOXIN / TOXIN RECEPTOR / BACTERIAL INFECTION / GUANYLYL CYCLASE / 毒素受容体 / グアニル酸シクラーゼ |
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| Research Abstract |
Heat-stable enterotoxin receptor (STaR/GC-C) is a member of membrane-associated guanylyl cyclase (GC) family. As compared with other GC receptors, following GC catalytic domain, STaR has prolonged carboxy-terminal tail which is about 60 amino acids longer than NPR-A (CC-A) and NPR-B (CC-B), and about 30 amino acids longer than GC-D, retGCl (GC-E), and retGC2 (GC-F). To elucidate the functional role of the additional carboxy-terminal tail, we examined the GC activities of two truncate STaR mutants, CDELTA1015 and CDELTA1023, which lack Gu^1^0^1^5-Phe^1^0^5^0 and Lys^1^0^2^3-Phe^1^0^5^0, respectively. After incubation with I jiM STa, the cells expressing CDELTA1O15 and CDELTA1023 accumulated about 20- and 10-folds higher cGMP than the cells expressing wild-typc STaR.The basal level of cGMP contents were not different between the cells with wild-type STaR and STaR mutants. Furthermore, the difference of CC activity was not observed at protein expression level. In addition, removal of carboxy-terminal tail of STaR induced not only high maximum level of cGMP-production but also high potential level of cGMP-produciion. These results suggest that the carboxy-terminal region of STaR might have an inhibitory function of STa-mediated GC activation, and therefore the lack of the carboxy-terminal region allowed to be activated high GC activity by STa.
STaR and its N-terminal extraceltular domain were prepared at a high level of expression from a system constructed of Sf21 insect cells and recombinant baculovirus. The recombinant STaR retained its binding activity to STa with a Rd value of 6.2x10^-^1^0^0M and cyclase catalytic activity at a level similar to those of STaR expressed jn mammalian cell lines, such as COS-7.
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