Siderophore-Mediated Iron-Uptake System in Vibrio parahaemolyticus and Its Relevance to Pathogenesis
| Project/Area Number |
05670257
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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 |
Bacteriology (including Mycology)
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| Research Institution | Okayama University, Faculty of Pharmaceutical Sciences |
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Principal Investigator |
YAMAMOTO Shigeo Okayama University, Faculty of Pharmaceutical Sciences Associate Prof., 薬学部, 助教授 (40033229)
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| Co-Investigator(Kenkyū-buntansha) |
SHINODA Sumio Okayama University, Faculty of Pharmaceutical Sciences Professor, 薬学部, 教授 (50029782)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Vibrio parahaemolyticus / Iron assimilation / Siderophore / Iron source / Outer membrane receptor / Transferrin utilization / Hemin utilization / Pathogenesis / ヘミン利用性 / ヘミンレセプター / 病原因子 / 外膜蛋白 |
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| Research Abstract |
1.The function of vibrioferrin (VE) as a siderophore in iron-starved Vibrio parahaemolyticus was demonstrated by uptake of [55Fe] ferric VF displaying kinetics typical of a protein receptor-mediated process. The iron uptake mediated by VF was blocked by uncouplers and ATPase inhibitors. The EDDA-plate assays showed that VF was inactive to other Vibrio Species except for V.alginolyticus, which was found later to synthesize VF.
2.The amounts of VF secreted to the culture supernatants were quantified by HPLC for 32 strains of V.parahaemolyticus isolated from different sources. The clinical isolates (n=8,33.6muM) produced VF 10-fold over the environmental isolates (n=22,3.9muM), indicating that the producibility of VF is advantageous of surviving and proliferating in human hosts.
3.The ability of VF to assimilate iron for growth from 30% iron-saturated human transferrin was demonstrated by comparison of growth rate between strain AQ 3354 and its spontaneous mutant defective in VF synthesis.
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This suggests that the organism may utilize such a source of host iron through the action of VF during in vivo survival and proliferation.
4.Under iron-restricted conditions, V.parahaemolyticus expressed two major outer membrane proteins of 78 and 83 kDa. Autoradiographic analysis of outer membrane preparations previously incubated with [55Fe] -VF revealed a single radiolabeled band, in which the 78-kDa protein was detected predominantly. The 78-kDa protein was cleaved by the treatment of whole cells with proteinase K,indicating its cell surface-exposed location. These results suggest that the Fe-VF binding protein of 78 kDa may function as the receptor for Fe-VF.Immunoblot analysis using the antiserum raised against the purified 78-kDa protein indicated that the molecular mass and antigenic properties of the protein were highly conserved among this species.
5.Several clinical isolates were examined for their ability to utilize either hemin or hemoglobin as a sole source of iron. Both compounds appeared to be equally good iron sources. The hemin-agarose batch affinity method allowed us to identify the 83-kDa protein as the hemin-binding protein.
6.Possession of two iron accquisition systems may be important at different stages or sites of infection, or as insurance against a mutational loss of one of them. The preparation of mutants defective of either or both of these receptor proteins is under progress to evaluate the contribution of these iron uptake systems to the physiology and infectious process of V.parahaemolyticus. Less
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Report
(3 results)
Research Products
(12 results)
