Mtl1 O-mannosylation mediated by both Pmt1 and Pmt2 is important for cell survival under oxidative conditions and TOR blockade

► Mtl1 is a sensor highly O-mannosylated by the O-mannosyltransferases Pmt2, Pmt1 and Pmt4 in Saccharomyces cerevisiae. ► O-mannosylation is important in the oxidative response and upon TOR blockade. ► Mtl1 physically interacts with Rom2 (a GTP exchange factor for Rho1). ► The absence of both Pmt2 and Pmt1 make cells sensitive to rapamycin and hydrogen peroxide. ► Mtl1 stability is influenced by both Pmt1 and Pmt2.