Summary of phenotypes observed for indicated histone allelesa

SubstitutionGrowth in absence of wild typeribosomal DNA silencingTelomeric silencingGrowth on HU
WT H3/H4++++++++++++
H4 K31A++++++++++++++
H4 K31R+++++++++++++++
H4 K31Q++++++++++++++
H4 K59A+++++++
H4 K59R+++++++++
H4 K59Q++++++++
H4 K77A++++++++++++
H4 K77R++++++++++++++
H4 K77Q++++++++++++++
H4 K79A++++++++
H4 K79R++++++++++++
H4 K79Q++++++++
H3 K56A++++++++
H3 K56R++++++++++
H3 K56Q++++++++
  • a The mutants were analyzed and their phenotypes were scored arbitrarily with respect to wild type. For a given process, wild type was denoted +++, and those mutants with a negative effect were scored as ++ or +, depending on the severity of the mutation. Alleles that induced an increase in silencing are indicated with ++++ or +++++, the latter of which corresponds to almost-complete repression of the reporter gene.