Bacteriophage D108 is a temperate, transposable, mutator phage similar to phage Mu. These heteroimmune phages have 37 kb linear, double-stranded DNA genomes which are over 90% homologous. / We have isolated four independent insertions of an entire thermoinducible D108 c ts10 phage genome in the low-copy plasmid pSC101. We also characterized a previously isolated Mu c ts62 insertion in the same plasmid replicon. Fine-structure analysis of these insertions showed that lytically transposing Mu and D108 genomes caused 5 bp duplications of the target site. In addition, we cloned and sequenced the terminal 800 bp of the right end of D108, a region important for the transposition of the phage genome. This analysis has delineated the critical DNA sequences required for D108 transposition, and has also indicated that these sequences are not entirely homologous to those of phage Mu, despite the fact that the phages can transpose each other's DNA. Moreover, a 520 bp insertion of DNA found in the right end of D108, but not Mu, has also been characterized, and has begins 72 bp from the right end of D108, immediately adjacent to the cis -acting sequences required for D108 transposition. This insertion does not appear to be an insertion element, but rather an extra gene in the right end of D108 whose function is apparently non-essential for D108 growth. The sequence differences and rearrangements between Mu and D108 in this region indicate a complex evolutionary relationship between these phages at their right extremities. / In addition to characterizing the DNA differences between Mu and D108, we have also examined a difference occurring at the protein level. The L gene products of Mu and D108 have different molecular weights, but are encoded from a region of homology between the two phages. We cloned a region of D108 DNA that was able to rescue amber mutations in the L gene of Mu by homologous recombination, but not complement Mu L amber phages in vivo. This region produced a gene product which was truncated at the carboxy terminus, but was able to cross-react with anti-Mu phage serum. The production of this truncated protein was lethal to growing Escherichia coli cells, apparently interfering with cell wall biosynthesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.75453 |
| Date | January 1987 |
| Creators | Szatmari, George B. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Microbiology and Immunology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000547825, proquestno: AAINL44439, Theses scanned by UMI/ProQuest. |
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