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Bacteriophage 434 Hex Protein Prevents RecA-Mediated Repressor Autocleavage
Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
* Author to whom correspondence should be addressed.
Received: 16 November 2012; in revised form: 14 December 2012 / Accepted: 17 December 2012 / Published: 9 January 2013
Abstract: In a λimm434 lysogen, two proteins are expressed from the integrated prophage. Both are encoded by the same mRNA whose transcription initiates at the PRM promoter. One protein is the 434 repressor, needed for the establishment and maintenance of lysogeny. The other is Hex which is translated from an open reading frame that apparently partially overlaps the 434 repressor coding region. In the wild type host, disruption of the gene encoding Hex destabilizes λimm434 lysogens. However, the hex mutation has no effect on lysogen stability in a recA− host. These observations suggest that Hex functions by modulating the ability of RecA to stimulate 434 repressor autocleavage. We tested this hypothesis by identifying and purifying Hex to determine if this protein inhibited RecA‑stimulated autocleavage of 434 repressor in vitro. Our results show that in vitro a fragment of Hex prevents RecA-stimulated autocleavage of 434 repressor, as well as the repressors of the closely related phage P22. Surprisingly, Hex does not prevent RecA‑stimulated autocleavage of phage lambda repressor, nor the E. coli LexA repressor.
Keywords: bacteriophage; RecA; lysogeny
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Shkilnyj, P.; Colon, M.P.; Koudelka, G.B. Bacteriophage 434 Hex Protein Prevents RecA-Mediated Repressor Autocleavage. Viruses 2013, 5, 111-126.
Shkilnyj P, Colon MP, Koudelka GB. Bacteriophage 434 Hex Protein Prevents RecA-Mediated Repressor Autocleavage. Viruses. 2013; 5(1):111-126.
Shkilnyj, Paul; Colon, Michael P.; Koudelka, Gerald B. 2013. "Bacteriophage 434 Hex Protein Prevents RecA-Mediated Repressor Autocleavage." Viruses 5, no. 1: 111-126.