1996 Fiscal Year Final Research Report Summary
Pathogenesis and molecular genetics of expression of iron acquisition systems in Vibro parahaemolyticus
| Project/Area Number |
07670312
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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 | Okayama University |
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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) |
1995 – 1996
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| Keywords | Vibrio parahaemolyticus / Iron acquisition / Iron-repressible gene / Repressor protein / Exocellular protease / Molecular cloning / Pathogenic factor / Mutant |
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| Research Abstract |
1. The 83-kDa iron-repressible outer membrane protein which binds hemin was purified and the antiserum against this protein was raised in rabbits. Immunoblot analysis using this antiserum indicated that the molecular mass and antigenic properties of the protein were highly conserved among this species.
2. A total of 109 V.parahaemolyticus strains isolated from different sources were examined for their activity to produced vibrioferrin in spend cultures, which was determined by a new developed HPLC method. Vibrioferrin was detected in most of the strains tested (95.2%). The mean value <plus-minus> SD of vibrioferrin in the clinical isolates (n=44) was 742.7 <plus-minus> 46.7 muM in sup./OD660, signifcantly different with p<0.01 from the mean values in food isolate (386.5 <plus-minus> 43.6, n=35) and environmental isolates (378,8 <plus-minus> 37.2, n=25). These results suggest that the higher productivity of clinical isolates may afford a significant selective advantage for growth in cond
… More
itions of iron-limitation such as exist in the in
3. Manganese resistant mutants of V.parahaemolyticus WP1 were isolated and characterized. The mutants expressed the 78- and 83-kDa outer membrane proteins independently of iron, suggesting the existence of an Fur-regulon. The fur gene, encoding an iron-regulatory protein has been cloned and sequenced. Its product showed a high degree of homology to known Fur sequence.
4. Exocellular protease activity of V.parahaemolyticus strains was significantly enhanced when they were grown under iron-limited conditions. Some manganese resistant mutants exhibited higher protease activity than the wild type strain WP1 even when grown under iron sufficient conditions, suggesting that expression of the gene encoding a protease (s) may be regulated by the Fur.Further study is required to clarify as to what kind of protease gene is regulated by Fur, since the presence of four proteases has been reported for this species.
Many clones which may have genes regulated by Fur were isolated by Fur titration assay method. Further nucleotide sequence analysis of these genes may lead to identification of iron-responsive genes and to cloning of the whole genes responsible. Less
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