Table II. Sap30 and Cth1 require cyclophilin A to suppress ess1^ts mutations.

Plasmid	Suppression of ess1 cpr1 double mutanta		CsA sensitivity of ess1ts strain at 37°Cb
Vector	no	(13%, n = 15)	n.d.
YEpESS1	yes	(43%, n = 23)	resistant
pYKL005C	yes	(31%, n = 26)	resistant
pFCP1	yes	(55%, n = 20)	resistant
pSAP30	no	(0%, n = 17)	sensitive
pCTH1	no	(0%, n = 7)	sensitive
pCPR1	yes	(50%, n = 4)	sensitive
pCaRPB7	yes	(33%, n = 12)	resistant

^aDiploid strain ess1^A144T/ESS1 cpr1Δ::LEU2/CPR1 was transformed with the multicopy suppressors or control plasmids (pRS426 vector, YEpESS1). Cells were sporulated and at least 20 tetrads were dissected. Similar data were obtained with the ess1^H164R allele (not shown). Segregants were replica-plated to medium lacking leucine at 37°C to detect those carrying the cpr1Δ::LEU2 allele, to medium lacking uracil to detect those containing the indicated URA3 plasmids, and to 5-FOA-medium to test the ability to lose the suppressor plasmid. 5-FOA-resistant cells are inferred to contain wild-type ESS1 rather than ess1^A144T. The values (% suppression) are given as the percentage of cells that are viable at 37°C and are 5-FOA^S among total segregants that are Leu⁺ (contain the cpr1 disruption) and Ura⁺ (contain the suppressor plasmid); n = total number of Leu⁺ Ura⁺ segregants. Maximum values would be 50% (the ess1^ts/ESS1 alleles segregate 2:2).

^bResults are for two ess1^ts strains (A144T and H164R). Sensitivity was tested on plates containing up to 100 µg/ml CsA. n.d. = not determined, since the ess1^ts mutant lacking a suppressor is inviable at 37°C.