Specific Inhibition of Elm1 Kinase Activity Reveals Functions Required for Early G₁ Events

Volume 23, no. 17, p. 6327-6337, 2003. We have been unable to reproduce a control experiment reported in this paper. Specifically, we found that 25 μM 1-naphthol-methyl PP1 (1NM-PP1) causes a G₁ delay in wild-type cells that is similar to the delay observed in elm1-as cells. While attempting to reproduce this control, we found that addition of supplemental adenine to yeast extract-peptone-dextrose (YPD) growth medium significantly reduces the effects of 1NM-PP1 on wild-type cells. Since our strains are ade⁻ and grow slowly on YPD medium, we often supplement the media with additional adenine. The addition of adenine to 100 mg/liter largely eliminates the G₁ delay observed in wild-type cells in the presence of 25 μM 1NM-PP1. We also found that the defects in septin organization that we observed before bud emergence were seen only at high concentrations of 1NM-PP1 (25 μM). They may therefore be the combined result of full inhibition of elm1-as and partial inhibition of other kinases. Alternatively, high concentrations of 1NM-PP1 may be necessary to achieve full inhibition of elm1-as. The other results of the paper are unaffected.