An accumulation of poly-sumoylated conjugates renders the <i>ulp2Δ</i> mutants more sensitive to hyperosmotic stress.

<p><i>a</i>, osmo-sensitivity of wild type (MHY500) and MHY500-derived mutants <i>ubc9-1</i>, <i>ulp1-333</i> and <i>ulp2Δ</i>, was measured by comparing the growth of serial diluted exponentially growing yeast cells on YPD plates with or without the addition of 1 M sorbitol. <b><i>b</i></b>, osmo-sensitivity of wild type (JD-52) and JD-52 derived mutants either accumulating poly-sumoylated species (<i>ulp2Δ</i>) or incapable of forming poly-sumoylated species (<i>smt3^K11,15,19R</i> and <i>ulp2Δ</i>/<i>smt3^K11,15,19R</i>) was similarly measured.