Genome-wide lethality screen identifies new PI4,5P2 effectors that regulate the actin cytoskeleton.
To further understand the roles played by the essential phosphoinositide PI4,5P(2), we have used a synthetic lethal analysis, which systematically combined the mss4(ts) mutation, partially defective in PI4P 5-kinase activity, with each of approximately 4700 deletion mutations. This genomic screening technique uncovered numerous new candidate effectors and regulators of PI4,5P(2) in yeast. In particular, we identified Slm1 (Yil105c), a previously uncharacterized PI4,5P(2) binding protein. Like Mss4, Slm1 and its homolog Slm2 (Ynl047c) were required for actin cytoskeleton polarization and viability. Co-immunoprecipitation experiments revealed that Slm1 interacts with a component of TORC2, a Tor2 kinase-containing complex, which also regulates the actin cytoskeleton. Consistent with these findings, phosphorylation of Slm1 and Slm2 was dependent on TORC2 protein kinase activity, both in vivo and in vitro, and Slm1 localization required both PI4,5P(2) and functional TORC2. Together, these data suggest that Slm1 and Slm2 function downstream of PI4,5P(2) and the TORC2 kinase pathway to control actin cytoskeleton organization.
Audhya
Anjon
A
Department of Cellular and Molecular Medicine, The Howard Hughes Medical Institute, University of California, San Diego School of Medicine, La Jolla, CA, USA.
Loewith
Robbie
R
Parsons
Ainslie B
AB
Gao
Lu
L
Tabuchi
Mitsuaki
M
Zhou
Huilin
H
Boone
Charles
C
Hall
Michael N
MN
Emr
Scott D
SD
D000199:Actins / Q000378:metabolism*; D016764:Cell Polarity; D002470:Cell Survival; D003599:Cytoskeleton / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005804:Genes, Lethal; D016678:Genome; D047468:Immunoprecipitation; D009154:Mutation; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor); D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion
D000199:Actins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D029701:Saccharomyces cerevisiae Proteins; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C489795:MSS4 protein, S cerevisiae