Fig. 6: Dma1 functions in parallel with phosphatase calcineurin in inhibition of polar growth in the presence of DNA replication stress.

a Calcineurin is not involved in Tip1 ubiquitination upon DNA replication stress induced by HU. Modification of ubiquitinated Tip1 was detected in indicated strains. b Additive effect of dma1Δ and ppb1Δ on cell length upon defective DNA replication induced by pol1-1546 mutation. Cells with indicated genotypes were either cultured at 25 °C or shifted from 25 to 37 °C for 6 h. Live images were captured and cell length of unseptated cells was measured. Pooled data from three independent experiments are shown as mean ± SD; n indicates total cell numbers measured for each strain; p values were determined by two-tailed unpaired t-test. c, d Viability of colonies challenged with DNA replication stress. Yeast strains with indicated genotypes were first grown as in (b), then spotted onto YES plates containing Phloxine B (c), or normal-looking cells of each strain were picked and placed on YES plates using a micromanipulator. Plates were incubated at 25 °C for >3 days. The frequency of viable colonies was calculated based on pooled data from 3 (for 25 °C samples) or 4 (for 37 °C-treated samples) biologically independent replicates (d). Pooled data are shown as mean ± SD; p values were determined by two-tailed unpaired t-test. Phloxine B was used to stain dead cells. e Model for Dma1-dependent signaling pathway to suspend polar growth upon DNA replication or DNA damage stress. At cell ends, ubiquitination of Tip1 by Dma1 predominantly through K63 linkages impedes polar factors (such as Tea4) to accumulate at cell ends and restrain polar growth when DNA replication or damage checkpoints are activated.