TABLE 3.

T7 gene 4 product (helicase/primase) is not required for efficient double strand break repair^a

Extract	Genomic DNA	Donor DNA	Titer	Repairb (%)
None	Intact	None	1.7 × 105
	Cut	None	2.7 × 102	0.2
Wild type	Intact	None	8.9 × 106
	Cut	None	2.5 × 104	0.3
recA	Intact	None	7.5 × 106
	Cut	None	6.6 × 104	0.9
Wild type	Intact	+	8.7 × 106
	Cut	+	3.3 × 106	38
recA	Intact	+	9.4 × 106
	Cut	+	2.5 × 106	27

^aT7X DNA was digested with XhoI to place a double strand break in the ligase gene (cut DNA); 1.5 nmol of T7X DNA in the form of intact or cut genomes was incubated in the in vitro repair system with 1.5 nmol of BstXI-digested T7 6⁻ ss⁻ DNA as donor. The reactions were carried out without extracts or with extracts made from either T7 ΔA 3⁻ 4⁻-infected E. coli wild-type or T7 ΔA 3⁻ 4⁻-infected E. coli recA. Reaction products were packaged and plated on wild-type E. coli. 

^bRatio of phage counts from reactions with cut DNA to those with intact DNA.