ANALYSIS OF THE DNA :BINDING PROPERTIES OF BACTERIOPHAGE P1 Cl REPRESSOR AND BOF MODULATOR PROTEINS 'UTILIZING A COMPARATIVE SELEX TECHNIQUE

Abstract

Bacteriophage P1 cycles between lytic and lysogenic states upon infection of a host bacteria. P1 maintains its lysogenic stage by suppressing gene expression from several lytic genes. Bacteriophage P1 C1 repressor protein binds to a family of operator sequences to regulate gene expression. Protein binding to these operator sites is regulated in a unique way by the P1 Bof protein. Bof protein enhances the DNA binding capability of C1 repressor by forming a ternary complex with Cl repressor and its cognate DNA. These DNA binding interactions are characterized by looking at the variability in C1 repressor binding sites utilizing a partially randomized oligonucleotide library based on a sequence logo constructed from an alignment of the natural C1 Operator sites and recombinant GST(glutathione S-Transferase) fusion C1 repressor and Bof proteins for SELEX (Systematic Evolution of Ligands by Exponential enrichment) experiments. The consensus sequence of oligonucleotides selected is A6TTGCICTAATA5. Palindromes are not important for binding, as previously hypothesized. A different hypothesis, emphasizing the role of DNA bending is discussed.