Synergistic action of three recombination gene products of bacteriophage T4, uvsX, uvsY, and gene 32 proteins.

Previously we proved that uvsX protein catalyzes reactions similar to those thought to occur during T4 recombination (Yonesaki, T., Ryo, Y., Minagawa, T., and Takahashi, H. (1985) Eur. J. Biochem. 148, 127-134; Yonesaki, T., and Minagawa, T. (1985) EMBO J. 4, 3321-3327). Now we have found that uvsY protein stabilizes binding of uvsX protein and single-stranded DNA and weakly stimulates those reactions catalyzed by uvsX protein, although it has little activity, if any, by itself. Gene 32 protein also stimulates them weakly at low concentrations, but is strongly inhibitory at high concentrations (Yonesaki, T., and Minagawa, T. (1985) EMBO J. 4, 3321-3327; Formosa, T., and Alberts, B. M. (1986) J. Biol. Chem. 261, 6107-6118). This inhibition is counteracted by uvsY protein. The highest efficiency of uvsX protein is achieved by the co-existence of a small amount of uvsY protein and a large amount of gene 32 protein. We discuss the mechanism and the role of the three proteins in recombination.