TABLE 2.

Histone H3 mutants that derepress the CHA1 promoter

Mutant	Mutation(s) in H3 sequence	Location of mutation	ts mutant	sin− mutant
hht2-3NTa	K4E, V35A, K37R	N terminus	−	−
hht2-2NTb	T11I, G33C	N terminus	+	+
hht2-RG	R69G	Histone fold domain, α-helix 1	−	+
hht2-FEc	F104S, E105G	Histone fold domain, α-helix 2	+	+
hht2-AG	A111G	Histone fold domain, α-helix 2	+	+
hht2-AT	A111T	Histone fold domain, α-helix 2	−	−

^aSeparated K4E and V35A K37R (the latter was not separated into individual mutations) mutants each show modest derepressing effects, which are approximately additive in the hht-3NT mutant.

^bSeparated T11I and G33C mutants show only modest derepressing effects compared to the parental mutant. Furthermore, neither mutation causes temperature sensitivity in the host strain or is a sin⁻ mutation (data not shown).

^cSeparated F104S and E105G mutants show only modest derepressing effects compared to the parental mutant. Furthermore, neither mutation causes temperature sensitivity in the host strain. The F104S mutant shows no sin⁻ phenotype, and the E105G mutant is a weak sin⁻ mutant (data not shown).