| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
This study was performed to elucidate the mechanisms of size- and shape-determination in supramolecular structures by using lambda phage as the material.
My previous studies have shown that the major capsid protein gpE can assemble into five classes of structures having various size and shape, depending on the missense mutation it contains. In this study I have clarified the structure-function relationship of gpE and established a material basis for the explanation of the determination mechanisms, through assignment of various mutations in the DNA base sequence. As concrete results, the positions of amber mutations at 43 sites have been determined completely. Moreover, I have sequenced 28 of the 31 missense mutants which produce head-related structures of various size and shape. Among the latter mutants many are substitutions of Ser, Pro or Gly, which suggests that the functional sites of gpE are rich in <beta> -turns located on the surface of the molecule.
Our previous work has indicated that the tail length is determined by the length of the "ruler protein" gpH. In this study thirty mutants having deletions of various size in the middle part of this gene were made by in vitro genetic manipulation. Twelve of them were found to produce phage particles with short tails, which shows that tail assembly proceeds in most cases as long as the deletions are in-frame. Of these twelve phage particles two have fragile tail tips, whereas the rest ten are defective in DNA injection. Therefore, the middle part of gpH seems to play an important role in these functions, while it is dispensable in tail assembly. Since the length of the tail tube is roughly proportional to the number of amino acid residues of gpH, the whole molecule of gpH seems to function as a ruler to measure the tail length.
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