TABLE 1.

Biochemical and genetic analysis of RecJ mutants

RecJ allele	Mutated motif	Nuclease activity (U/mg of protein)a	Protein stability (%) after 10-h chaseb	UV survival (%) at 10 J/m2 in:				Genetic effect
				STL3803 (recJ mutant)c		JC8679 (recJ+)d
				Without IPTG	With IPTG	Without IPTG	With IPTG
Vector		5.7		0.0027	0.0085	17	17
recJ+		7,100	42	36	20	18	20
recJD79A	1	16	22	0.0031	0.0016	7.8	1.1	Dominant
recJD81A	1	18	59	0.0035	0.0061	8.7	1.4	Dominant
recJD83A	1	14	44	0.0018	0.0011	11.0	1.2	Dominant
recJD137A	2	13	25	0.0014	0.0035	9.8	9.2	Recessive
recJD160A	3	7.5	52	0.0059	0.0030	12	1.8	Dominant
recJH161A	3	15	54	0.0088	0.0015	16	13	Recessive
recJH162A	3	19	33	0.0019	0.0033	20	10	Recessive
recJD236A	4	11	29	0.0069	0.0059	0.61	0.48	Dominant
recJR401A	6	18	23	0.0076	0.0016	22	16	Recessive
recJH429A	7	63	39	0.0038	0.085	18	22	Recessive

^aNuclease activity in crude extracts of various pWSK29-RecJ plasmid transformants (of STL327/pGP1-2) after induction of T7 promoter. Data are averages of two to four experiments. 

^bPercentage of RecJ protein retained after 10-h chase as described in Materials and Methods after T7 promoter induction of various pWSK29-RecJ derivatives in STL327/pGP1-2 strains. 

^cComplementation tests of pWKS30-RecJ derivatives, with and without induction of the lac promoter. Data are averages of two to four experiments. 

^dDominance tests of pWKS130-RecJ derivatives, with and without induction of the lac promoter. Data are averages of two to four experiments.