The role of the bacteriophage T4 gene 32 protein in homologous pairing.

T Kodadek

doi:10.1016/s0021-9258(17)45311-7

Abstract

The gene 32 protein of the bacteriophage T4 is required for efficient genetic recombination in infected Eschericia coli cells and strongly stimulates in vitro pairing catalyzed by the phage uvsX protein, a RecA-like strand transferase. This helix-destabilizing factor is known to bind tightly and cooperatively to single-stranded DNA and to interact specifically with the uvsX protein as well as other phage gene products. However, its detailed role in homologous pairing is not well understood. I show here that when the efficiency of uvsX protein-mediated pairing is examined at different gene 32 protein and duplex DNA concentrations, a correlation between the two is found, suggesting that the two interact in a functionally important manner during the reaction. These and other data are consistent with a model in which the gene 32 protein binds to the strand displaced from the recipient duplex during pairing, thereby stabilizing the heteroduplex product. An alternative model in which the gene 32 protein replaces UvsX on the invading strand, thereby freeing the strand transferase to bind to the displaced strand, is also considered.

Highlights

From the Department of Chemistry and Biochemistry and the Clayton Foundation Biochemical Institute, University of Texas, Austin, Term- 78712
An alternative model in which the gene 32 protein replaces UvsX on the invading strand, thereby freeing the strand transferase to bind to the displaced strand, is considered
In vitro studies have demonstrated that such proteins are able to significantly stimulate the rate of strand exchange between homologous single and double-stranded DNAs catalyzed by “strand transferase” proteins (l-4), a process central to the recombination cycle

Summary

Introduction

I show here that when the efficiency of uvsX protein-mediated pairing is examined at different gene 32 protein and duplex DNA concentrations, a correlation between the two is found, suggesting that the two interact in a functionally important manner during the reaction. These and other data are consistent with a model in which the gene 32 protein binds to the strand displaced from the recipient duplex during pairing, thereby stabilizing the heteroduplex product.

Results

Conclusion