2005 Fiscal Year Final Research Report Summary
Chemical studies on Bacillus competent factor
| Project/Area Number |
16580087
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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 |
Bioproduction chemistry/Bioorganic chemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
SAKAGAMI Youji Nagoya University, Graduate School of Bioagricultural Sciences, Department of Applied Molecular Biosciences, Professor, 大学院・生命農学研究科, 教授 (80107408)
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| Co-Investigator(Kenkyū-buntansha) |
OJIKA Makoto Nagoya University, Graduate School of Bioagricultural Sciences, Department of Applied Molecular Biosciences, Professor, 大学院・生命農学研究科, 教授 (50152492)
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| Project Period (FY) |
2004 – 2005
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| Keywords | quorum sensing / Bacillus subtilis / competence / peptide pheromone / tryptophan / isoprenoid / posttranslational modification |
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| Research Abstract |
Bacteria produce and respond to signal molecule depending on their cell density. This process is called "quorum sensing". ComX pheromone controlled by quorum sensing activates a natural genetic competence in Bacillus subtilis. ComX pheromone is an oligopeptide with a posttranslational modification. It was suggested that ComX pheromone is modified with an isoprenoid at the tryptophan residue, however, the complete chemical structure has been unknown. To determine the precise nature of the ComX modification, we chose to work with the pheromone from B. subtilis strain RO-E-2 having only six amino acids. Considering the molecular weight and the observed chemical shifts of tryptophan residue, we propose the plane structure for the tryptophan residue that a geranyl goup connects to 3-position of tryptophan and the alpha amino group connects to 2-positiuon to make a pyrrole ring (3a-geranyl-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid). We also estimated the absolute structure of the geranyl tryptophan. To confirm this chemical structure, we synthesized optically active geranyl tryptophan and the corresponding ComX_<RO-E-2> peptide. The synthetic peptide showed an identical ^1H NMR spectrum to that of the natural pheromone. We also observed that the synthetic peptide showed a similar biological activity to ComX_<RO-E-2>. Although the isoprenoidal modification of cysteine is well known, this is the first example of posttranslationally isoprenylated tryptophan in peptide.
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