Decreased PKA activity can increase proliferation of cells lacking mtDNA.

<p>(A) Overexpression of cAMP phosphodiesterase Pde2p increases the fitness of cells lacking mtDNA. Strain BY4743 (<i>WT</i>) was transformed with empty, high-copy vector pRS426 or plasmid b89 (2μ-<i>PDE2</i>). Strains were tested for their response to mtDNA loss by incubation in selective medium lacking or containing 25 μg/ml EtBr, with subsequent incubation on solid SC-Ura medium for 2 d. (B) Lack of Tpk3p increases the fitness of cells lacking mtDNA. Strains BY4742 (<i>WT</i>), CDD884 (<i>tpk1Δ</i>), CDD885 (<i>tpk2Δ</i>), CDD886 (<i>tpk3Δ</i>), CDD908 (<i>tpk1Δ tpk3Δ</i>), CDD922 (<i>tpk2Δ tpk3Δ</i>), and CDD923 (<i>tpk1Δ tpk2Δ</i>) were tested for their response to mtDNA deletion with incubation on solid YEPD medium for 2 d. (C) Cells deleted of Gpa2p or Gpr1p exhibit increased fitness after mtDNA deletion. Strains BY4742 (<i>WT</i>), CDD886 (<i>tpk3Δ</i>), CDD849 (<i>gpa2Δ</i>), and CDD850 (<i>gpr1Δ</i>) were treated as in (B).