Cloning of uvsW and uvsY genes of bacteriophage T4

Abstract

Genetic and physiological studies of others have shown that bacteriophage T4 gene uvsW and uvsY map in a nonessential region of the genome between essential genes 24 (head) and 25–48 (baseplate), and are involved in recombination pathways. This paper reports the cloning of the uvsW and uvsY genes by the following strategy. Correlation of cleavage and genetic maps suggested that these genes should be carried by an 11.6-kb SlaI fragment that should also carry the essential baseplate genes 25–48. T4 cytosine-containing DNA was cleaved with Salt and fragments ligated into the SalI site in pBR322 Amp rTet 5 recombinant plasmids were screened for possession of the baseplate genes by marker rescue. Plasmids that rescue these essential genes were shown to carry the predicted SlaI 11.6-kb fragment in either orientation and to complement mutants in the uvsW and uvsY genes, protecting the mutant phage from inactivation by hydroxyurea or by methylmethane sulfonate. Partial restriction mapping, construction of deletion hybrid plasmids in vitro, and further complementation tests established the physical order of the uvsW and uvsY genes in relation to the baseplate genes 25–48 on the same fragment.