TABLE 1.

Relevant genotypes of haploid strains used in this study

Straina	HIS4 upstream alterationb	HIS4 coding sequence alterationc	Other relevant alterationsd	Referencee
AS4	WT	WT	WT	38
PD63	his4-Δ52	WT	WT	4
MW74	his4-Δ52	his4-203	WT	10
HF6	his4-202	his4-lopc	rad50S	8
DNY107	WT	WT	rad50S	8
DTK227	his4-C48	WT	WT	—
DTK321	his4-C48	WT	rad50S	—
DTK345	his4-C12	WT	WT	—
DTK351	his4-C12	WT	rad50S	—
DTK362	his4-C12d	WT	WT	—
DTK457	his4-CCGAT12	WT	WT	—
AS13	WT	WT	WT	38
PD57	his4-Δ52	WT	WT	4
PD80	his4-Δ52	his4-lopc	WT	4
DNY25	WT	his4-lopc	WT	26
HF4	WT	his4-ATC	rad50S	8
HF5	his4-202	WT	rad50S	8
DTK255	his4-C48	his4-lopc	WT	—
DTK292	his4-C48	WT	WT	—
DTK303	his4-C48	his4-203	WT	—
DTK322	his4-C48	his4-lopc	rad50S	—
DTK344	his4-C12	his4-lopc	WT	—
DTK350	his4-C12	his4-lopc	rad50S	—
DTK361	his4-C12d	his4-lopc	WT	—
DTK458	his4-CCGAT12	his4-lopc	WT	—

^aThe first 11 strains listed were derived by transformation from the haploid AS4, and the remainder were from the haploid AS13. 

^bThe upstream regulatory region of HIS4 in wild-type (WT) strains has binding sites for the transcriptional activators Rap1p, Bas1p, Bas2p, and Gcn4p, and strains with the his4-Δ52 allele have deletions at these sites. In his4-202 strains, the sequences deleted in his4-Δ52 were replaced with about 50 bp of telomeric sequences (49). In his4-C48 and his4-C12 strains, the wild-type upstream regulatory region was replaced with 48 or 12 copies, respectively, of CCGNN repeats (Fig. 1). Strains with the his4-C12d insertion are identical to those with his4-C12, except that the polylinker flanking the CCGNN repeats has been deleted. In strains with the his4-CCGAT₁₂ allele, the wild-type upstream regulatory region of HIS4 was replaced with 12 copies of CCGAT. 

^cThe his4-lopc allele is a 26-bp palindromic insertion at position 467 of the coding sequence. When strains heterozygous for this insertion are sporulated and dissected, high levels of postmeiotic segregation are observed, indicating that this marker results in a poorly repaired mismatch when located within a heteroduplex (26). The his4-203 allele is an insertion of about 50 bp of telomeric DNA at position 96 of the coding sequence (10). The his4-ATC allele is a single-base-pair change at position 3 of the coding sequence (3). 

^dWhen diploid strains homozygous for the rad50S mutation are sporulated, meiosis-specific DSBs associated with hot spots are formed, but the broken ends are not processed (1). 

^e—, strain constructed in this study.