Table 1. Spore viability and plasmid shuffling results for the DNA2 mutants.

Mutant allele	Amino acid change	Spore viability (%)	Spore with marker (%)	pRS314	pRS314GU + Glu	pRS314GU + Gal
Wild-type		89	52	+++	+++	+++
Group I
dna2-21	Q551E	94	48	+++	+++	+++
dna2-22	K680A	100	50	+++	+++	+++
Group II
dna2-23	D505N	94	42	+++	–	+++
dna2-24	H547A	54	19	+++	–	+++
dna2-15	R521K	90	44	+++	–	+++
Group III
dna2-25	DIEE640NIQQ	46	0	–	–	+/–
dna2-26	R521E	43	0	–	–	–
dna2-27	D657A	46	0	–	–	–
dna2-28	R734A	45	0	–	–	–

For analyses of viability of spores containing mutant DNA2 alleles, the diploid strain YJA1 (MATa/MATα DNA2/Δdna2::HIS3) was transformed with pRS304 (vector), pRS304-DNA2 (wild-type DNA2 in pRS304) and pRS304-dna2-X (X indicates the mutant allele shown above). The resulting diploid transformants were separately sporulated and tetrads were dissected. The percent spore viability was obtained by dividing the number of colonies grown by total tetrads. The viable colonies obtained were examined for the presence of both His⁺ and Trp⁺ markers. The ability of cells to grow after plasmid shuffling is shown as: –, no growth; +/–, 100- to 1000-fold less growth than wild-type; +++, growth like wild-type control. Plasmid shuffling tests were performed using plasmids in which the mutant DNA2 alleles were expressed using its native promoter (pRS314) or using the GAL1 promoter (pRS314GU) in medium containing glucose (+Glu) or galactose (+Gal).