The timing of host lysis is the only decision made in the bacteriophage lytic cycle. To optimize timing, double-stranded DNA phages use a 2-component lysis system consisting of a muralytic enzyme, the endolysin, and a small membrane protein, the holin, which controls the timing of lysis. The best characterized holin gene to date is the S gene of bacteriophage λ. One unusual feature of the S gene is that it produces two proteins of opposing function: the holin, S105, and the antiholin, S107. Raab et al isolated and characterized a number of S mutants, but all of them expressed both the holin and the antiholin; it is possible, then, that the true extent of the holin-holin interactions were masked by interactions with the antiholin. Thus, a large number of S105 mutants were created, and their phenotypes characterized in the absence of the antiholin. The interaction between those mutants and the wild-type were examined in an attempt to better understand what determines the timing of hole formation by S105. S105 and S107 differ only by two amino acids at the N-terminus; S107 has an additional Met-Lys sequence. Previous studies have shown that S107 may have a different topology to S105, where the N-terminus of S107 is located in the cytoplasm and is cannot flip through the membrane because of the extra cationic side chain. This study investigates the role of the N-terminal transmembrane domain of the S proteins in terms of hole formation and its role in the antiholin character of S107. Previous results suggest that S105 forms hole via a large oligomeric structure termed the “death raft”. The death raft model states that after S105 is inserted into the membrane, it forms “rafts”, which grow in size until a spontaneous channel forms leading to depolarization of the membrane and hole formation. This study investigates the pathway of hole formation at the single-cell level, using a C-terminal fusion of S105 and green fluorescent protein, and attempts to address several of the predictions posed by the death raft model.

Frankfurt (Main), Univ., Diss., 2002

Techn. Universiẗat, Diss., 2000--Darmstadt.

University, Diss., 2002--Heidelberg.

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 49-54). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11779

Universiẗat, Diss., 2002--Frankfurt (Main).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 166-178).

No description available.

No description available.

The CLAS Collaboration is using the p(e, e′ K+ p)π- reaction to perform a measurement of the induced polarization of the electroproduced Λ(1116). The parity-violating weak decay of the Λ into pπ- (64%) allows extraction of the recoil polarization of the Λ. The present study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton. CLAS allows for a large kinematic acceptance in Q2 (0.8 ≤ Q2 ≤ 3.5 GeV2 ), W (1.6 ≤ W ≤ 3.0 GeV), as well as the kaon scattering angle. In this experiment a 5.499 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for theoretical models of the electromagnetic production of kaon-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances.