1988 Fiscal Year Final Research Report Summary
Supersecondary structure assembled with -helices
| Project/Area Number |
62580219
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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 |
生物物性学
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| Research Institution | Kyoto University |
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Principal Investigator |
TAKAHASHI Sho Institute for Chemical Research, Kyoto University, 化学研究所, 教授 (20022593)
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| Co-Investigator(Kenkyū-buntansha) |
OOI Tatsuo Emeritus Professor, Kyoto University, 名誉教授 (00027004)
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| Project Period (FY) |
1987 – 1988
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| Keywords | -Helix / Supersecondary structure / Coiled-coil / Bacteriophage T3 / Tail fiber / Recombinant DNA / Denaturation and renaturation / アミノ酸配列解析 |
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| Research Abstract |
Supersecondary structure assembled with elementary secondary structures in a regular fashion is the most simple tertiary structure of protein. We focussed our attention onto a paralled assembly of alpha-helices: coiledcoil structure.
From electron microscopic observations, tail fibers of bacteriophage T3 were suspected to have an alpha-helical coiled-coil. Analysis of amino acid sequence of the tail fiber with an aid of a computer to search an every possibility to pack alpha-helices together, coupled with biochemical evidence, revealed a unique supersecondary structure, three alpha-helical coiled-coil as the structure of the thin rod segment. The structure is most stable when the packing of the helices was parallel and in register, and the coiled-coil region started at Ala 140 and ended at Ile 276. Each alphahelix interacts with others with hydrophobic residues inside and with an arrangement of complementarily charged side chains to form salt bridges between the helices.
The tail fiber is a product (gp17) of gene 17 of T3 phage. A recombinant DNA which contained gene 17 was constructed and expressed efficiently in E. coli cells. gp17 obtained as protein bodies was solubilized with guanidinium chloride. Careful dilution of the solubilized and denatured gp17 gave a trimeeric protein, which showed full biological infectivity on a complementation test using a mutant T3 lacked active gene 17.
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