TABLE 2.

Effects of overexpression of the N- and C-terminal domains of Sir3p on telomeric position effect and requirements for enhanced repression: fraction of 5-FOA^R colonies upon introduction of overexpression plasmids^a

Strain	Plasmid	5-FOARb	Fold variation
AJL275-2AVR	pADH-SIR3N	3.0 × 10−2 (1.0 × 10−2–4.0 × 10−1)	40 (repression)
	pADH-SIR3C	3.0 × 10−5 (1.7 × 10−6–7.0 × 10−5)	30 (derepression)
	pADH-SIR3	7.0 × 10−2 (8.0 × 10−2–8.0 × 10−1)	90 (repression)
	pADH	8.0 × 10−4 (4.0 × 10−4–2.5 × 10−3)	1

^aThe AJL275-2AV_R strain, which carries URA3 adjacent to the V_R telomere, was transformed with the following 2μ-based plasmids: pADH-SIR3N, pADH-SIR3C, pADH-SIR3 (p2μ-ASIR3 [26]), and pADH (pAAH5). 

^bTranscriptional repression of URA3 was determined by measuring resistance to 5-FOA from a minimum of four independent transformants. The range of values is given in parentheses. The effects of Sir3C and Sir3N overexpression were confirmed with both URA3 and ADE2 reporters at both TelV_R and -VII_L in a range of strains, including UCC3107 and GA493 (6) as well as the AJL275 background.