The structure, function and regulation of the S gene of bacteriophage lambda /
| Main Author: | |
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | The plasmid pRG1 carrying the bacteriophage lambda lysis genes was mutated by hydroxylamine mutagenesis. Thirty-five sing-base change mutation within the S gene were analyzed from DNA sequence analysis. A model for localization of the S protein in the inner membrane can be derived with the use of various theoretical analyses. In this model there are three hydrophobic domains that span the inner membrane as a pair of not-neutral α-helices, with the 8 amino-terminal residues located in the periplasm. Mutations in amino acids that alter the charge were found in possible membrane-spanning regions, along with changes of glycine residues at predicted reverse turn region. Other mutation, involving no change in charge, were classified as neutral mutations; these mutations are located mainly within the proposed membrane spanning regions. All of these mutation in a loss of α-helical character and an increase in β-sheet character as predicted by Chou-Fasman analysis. A procedure was devised using a lambda phage deleted for the S and R genes that allowed 40 different mutations to be recombined on the lambda phage genome. Some missense alleles of the S gene exhibited a co-dominant phenotype. These results are interpreted to suggest that the S protein must oligomerize to be lethal. Upstream mutants also displayed dominant character. It is suggested that these mutations define a region of mRNA secondary structure, sdi (structure directed initiation), that controls the choice of initiation condons. Formation of the sdi structure occludes the Shine-Dalgarno sequence for the Met1 condon and results in initiation at the Met3 condon, leading to a 105 amino acid protein. This 105 residue protein is thought to be the lethal product of the S gene. In the model there might be an equilibrium between the formation and disruption of the sdi structure. With the sdi secondary structure denatured, initiation begins at the Met1 codon, resulting in a 107 residue product which is proposed to have an inhibitor function. Gene fusions of S to lacZ have been constructed and result in hybrid proteins with a carboxy-terminal region that retains β-galactosidase activity with the amino-terminal region for the S gene... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Biology." |
| Physical Description: | xiii, 147 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 132-146). |