Selection and design of high affinity DNA ligands for mutant single-chain derivatives of the bacteriophage 434 repressor

2001 ◽  
Vol 44 (3) ◽  
pp. 274-286 ◽  
Author(s):  
Tiebing Liang ◽  
Kehui Tan ◽  
Kang Chong ◽  
Zhiqing Zhu ◽  
Sándor Pongor ◽  
...  
Keyword(s):  
Single Chain ◽  
High Affinity ◽  
Bacteriophage 434 ◽  
Bacteriophage 434 Repressor ◽  
Derivatives Of ◽  
434 Repressor

scholarly journals The Bacteriophage 434 Repressor Dimer Preferentially Undergoes Autoproteolysis by an Intramolecular Mechanism

2005 ◽  
Vol 187 (16) ◽  
pp. 5624-5630 ◽  
Author(s):  
Barbara C. McCabe ◽  
David R. Pawlowski ◽  
Gerald B. Koudelka
Keyword(s):  
Dna Damage ◽  
Active Sites ◽  
Sos Response ◽  
Lambdoid Phage ◽  
Lambdoid Prophage ◽  
Operator Binding ◽  
Bacteriophage 434 ◽  
Bacteriophage 434 Repressor ◽  
434 Repressor ◽  
Intramolecular Mechanism

ABSTRACT Inactivation of the lambdoid phage repressor protein is necessary to induce lytic growth of a lambdoid prophage. Activated RecA, the mediator of the host SOS response to DNA damage, causes inactivation of the repressor by stimulating the repressor's nascent autocleavage activity. The repressor of bacteriophage lambda and its homolog, LexA, preferentially undergo RecA-stimulated autocleavage as free monomers, which requires that each monomer mediates its own (intramolecular) cleavage. The cI repressor of bacteriophage 434 preferentially undergoes autocleavage as a dimer specifically bound to DNA, opening the possibility that one 434 repressor subunit may catalyze proteolysis of its partner subunit (intermolecular cleavage) in the DNA-bound dimer. Here, we first identified and mutagenized the residues at the cleavage and active sites of 434 repressor. We utilized the mutant repressors to show that the DNA-bound 434 repressor dimer overwhelmingly prefers to use an intramolecular mechanism of autocleavage. Our data suggest that the 434 repressor cannot be forced to use an intermolecular cleavage mechanism. Based on these data, we propose a model in which the cleavage-competent conformation of the repressor is stabilized by operator binding.

scholarly journals Effect of Salt Shock on Stability of λimm434 Lysogens

2007 ◽  
Vol 189 (8) ◽  
pp. 3115-3123 ◽  
Author(s):  
Paul Shkilnyj ◽  
Gerald B. Koudelka
Keyword(s):  
Salt Stress ◽  
Ionic Composition ◽  
Monovalent Cation ◽  
Growth Media ◽  
Bacterial Cells ◽  
Salt Shock ◽  
Phage Production ◽  
Bacteriophage 434 ◽  
Bacteriophage 434 Repressor ◽  
434 Repressor

ABSTRACT The affinities of the bacteriophage 434 repressor for its various binding sites depend on the type and/or concentration of monovalent cations. The ability of bacteriophage 434 repressor to govern the lysis-lysogeny decision depends on the DNA binding activities of the phage's cI repressor protein. We wished to determine whether changes in the intracellular ionic environment influence the lysis-lysogeny decision of the bacteriophage λ imm434 . Our findings show that the ionic composition within bacterial cells varies with the cation concentration in the growth media. When λ imm434 lysogens were grown to mid-log or stationary phase and subsequently incubated in media with increasing monovalent salt concentrations, we observed a salt concentration-dependent increase in the frequency of bacteriophage spontaneous induction. We also found that the frequency of spontaneous induction varied with the type of monovalent cation in the medium. The salt-dependent increase in phage production was unaffected by a recA mutation. These findings indicate that the salt-dependent increase in phage production is not caused by activation of the SOS pathway. Instead, our evidence suggests that salt stress induces this lysogenic bacteriophage by interfering with 434 repressor-DNA interactions. We speculate that the salt-dependent increase in spontaneous induction is due to a direct effect on the repressor's affinity for DNA. Regardless of the precise mechanism, our findings demonstrate that salt stress can regulate the phage lysis-lysogeny switch.

Synthesis and mass spectrometric characterisation of the N-terminal (1-63) DNA-binding domain of the bacteriophage 434 repressor cI

1997 ◽  
Vol 3 (1) ◽  
pp. 151
Author(s):  
Piergiorgio Percipalle ◽  
Sandor Pongor ◽  
Sotir Zakhariev ◽  
Corrado Guarnaccia ◽  
Rosaria Saletti ◽  
...  
Keyword(s):  
Dna Binding ◽  
Mass Spectrometric ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Bacteriophage 434 ◽  
Bacteriophage 434 Repressor ◽  
434 Repressor
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