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|Title:||The Lipid-Containing Bacteriophage PR4: Posttranslational Processing of the Major Capsid Protein and Lipid Selection in Particle Assembly|
|Doctoral Committee Chair(s):||Cronan, J.E., Jr.,|
|Department / Program:||Microbiology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||PR4 is a bacteriophage that contains lipid bilayer membrane within its protein capsid. The hosts include Escherichia coli and Salmonella typhimurium.
I describe an investigation showing that capsid proteins P16 and P18 of bacteriophage PR4 are formed by post-translational processing of a portion of the major capsid protein P2. A polyclonal antibody raised against purified P2 reacted with P16 and P18 as well as P2. A monoclonal antibody reacted with both P2 and P18. The amino acid sequences of N-termini of P2 and P18 exactly matched indicating that P18 is the N-terminal fragment of processed P2. These data were confirmed by the analysis of the proteins encoded by various P2 nonsense and missense mutants. The 3129 bp MnlI-C fragment of PR4 genome was shown to encode P2 and the nucleotide sequence of this fragment was obtained and shown to contain a single continuous ORF encoding P2, thus excluding the possibility of introns or other post-transcriptional processing in production of P16 and P18. The MnlI-C DNA segment contained 7 ORFs sized $>$200 bp in addition to P2 gene and the genes encoding proteins P6 and P6A were mapped by marker rescue analysis.
Phage PR4 contains a lipid bilayer within the protein capsid. The phospholipids of the bilayer are derived from those of the host. I report that phage morphogenesis selects against the unusually bulky phospholipids synthesized by Escherichia coli grown in the presence of various sugar alcohols. These data indicate that assembly of the PR4 lipid bilayer is a selective process rather than the bulk appropriation of host membrane lipids. I also demonstrate that phage PR4 morphogenesis is compatible with the incorporation of several abnormal lipids, monoacylglycerol, diacylglycerol, and phosphatidylinositol into the phage particle.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1992.
|Date Available in IDEALS:||2014-12-17|