Ho HL, et al. (2008) Involvement of Saccharomyces cerevisiae Avo3p/Tsc11p in maintaining TOR complex 2 integrity and coupling to downstream signaling. Eukaryot Cell 7(8):1328-43
Abstract: Target of rapamycin (TOR) proteins are Ser/Thr kinases serving a central role in cell growth control. TORs function in two conserved multi-protein complexes, TORC1 and TORC2, while mechanisms underlying their actions and regulation are not fully elucidated. Saccharomyces TORC2, containing Tor2p, Avo1p, Avo2p, Avo3p/Tsc11p, Bit61p and Lst8p, regulates cell integrity and actin organization. Two classes of avo3(ts) mutants we previously identified both display cell integrity and actin defects, yet one is suppressed by AVO1 while the other by AVO2 or SLM1, defining two TORC2 downstream signaling mechanisms, one Avo1p-mediated and the other Avo2p/Slm1p-mediated. Employing these mutants we explored Avo3p functions in TORC2 structure and signaling. By checking binary protein interactions using co-immunoprecipitation we discovered differentially affected TORC2 composition and recruitment of downstream effectors Slm1p and Slm2p in different avo3(ts) mutants. These molecular defects can only be corrected by expressing AVO3 but not suppressors, highlighting the role of Avo3p as a structural and signaling scaffold for TORC2. Phenotypic modifications of avo3(ts) mutants by deleting individual Rho1p-GTPase activating proteins indicate that two TORC2 downstream signaling branches converge onto Rho1p activation. Results also suggest that Avo2p/Slm1p-mediated signaling but not Avo1p-mediated signaling links to Rho1p activation specifically through the Rho1p-guanine nucleotide exchange factor Tus1p.
|Status: Published||Type: Journal Article||PubMed ID: 18552287|
Topics addressed in this paper
Number of different genes curated to this paper: 17
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