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Thesis (M. Ph.)--Chinese University of Hong Kong. / Bibliography: 101-113 l.

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Bacteriophages are viruses that infect and propagate within bacteria by making use of the host’s biosynthetic machinery. With a global population of 1031, phages pose a significant influence on microbial populations. Studies of bacteriophage proteins can elucidate the influence that bacteriophages play on the evolution of bacteria, as well as, providing the basis for the use of phage proteins as possible therapeutics and bioengineering solutions. This study aims to investigate the structural and functional role of the HK97 phage protein gp74. Sequence alignments indicate that gp74 is related to homing HNH endonucleases. Homing endonucleases are predominantly double-stranded DNases, suggesting that gp74 mediates integration of phage genes into the host genome or may target foreign phage DNA. DNA digestion experiments with gp74 reveals that gp74 mediates non-specific double-stranded cleavage of lambda phage DNA and single strand cleavage of plasmid DNA. Our initial work demonstrates that HK97 gp74 is an HNH endonuclease.

Bacteriophages are viruses that infect and propagate within bacteria by making use of the host’s biosynthetic machinery. With a global population of 1031, phages pose a significant influence on microbial populations. Studies of bacteriophage proteins can elucidate the influence that bacteriophages play on the evolution of bacteria, as well as, providing the basis for the use of phage proteins as possible therapeutics and bioengineering solutions. This study aims to investigate the structural and functional role of the HK97 phage protein gp74. Sequence alignments indicate that gp74 is related to homing HNH endonucleases. Homing endonucleases are predominantly double-stranded DNases, suggesting that gp74 mediates integration of phage genes into the host genome or may target foreign phage DNA. DNA digestion experiments with gp74 reveals that gp74 mediates non-specific double-stranded cleavage of lambda phage DNA and single strand cleavage of plasmid DNA. Our initial work demonstrates that HK97 gp74 is an HNH endonuclease.

Abstract Rapid and reliable identification of microorganisms is of paramount importance for advancing homeland security. Mass spectrometry is emerging as an effective bioanalytical tool having unique capabilities in handing complex mixtures. Matrix-assisted layser desorption / ionization time-of-flight mass spectrometry ¡]MALDI/TOF MS¡^is commonly used in the analysis of bio-molecules owing to its merits of high sensitivity, wide mass range, and ease-of-operation. The objective of the first part of the thesis is to develop an analysis method to characterize the genus, strains, and subspecies of the infections gastroenteritis bacteria by using MALDI/TOF MS. MALDI/TOF MS can be applied to classify different microoganisms based on examination of ion patterns from different microoganisms and unique distinguishing protein ions as biomarkers for different strains. The second section, bacteriophages MS2 and T4 were used as materials for identification of their specific protein markers. Protocols including sample preparation, purification, combined in gel digestion and post source decay to which the mass spectrometer brought for analytical specificity were employed. According to the experimental results, classification of different microorganisms based on examination of ion patterns is feasible. Furthermore, the peak at m/z 5255 in the MALDI mass spectra of MS2 analysis and the peak at m/z 8600 of T4 can provide the unique distinguishing signals. The experimental mass spectral peaks were submitted to the database search, and one of these peaks was matched to a tail fiber assembly helper protein. Thus, the method developed and the mass spectra presented in this thesis can be potentially applied to the practical virus analysis.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

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