Genetic and biochemical interactions between the Arp2/3 complex, Cmd1p, casein kinase II, and Tub4p in yeast.
Arc35p, a component of the Arp2/3 complex, plays at least two distinct roles, regulating the actin cytoskeleton, but also microtubule function during cell division. Both functions involve calmodulin (CMD1). To investigate the pathway affecting microtubule function, we identified genes that are able to suppress the temperature-sensitive growth defect of the arc35-1 strain. Genes encoding gamma-tubulin (TUB4) or any subunit of casein kinase II (CKII) suppressed this growth defect, but did not suppress the growth defect of a mutant in another subunit of the Arp2/3 complex, arp2-1. We could also show a physical association of Arc35p with subunits of CKII, Cmd1p, and Tub4p. Based on the exclusive localization of Arc35p to the cytosolic Arp2/3 complex and on mutant phenotypes, we propose that the role of the Arc35p/CKII interaction might be to activate a cytosolic pool of gamma-tubulin, likely via calmodulin, for its nuclear and/or cytoplasmic functions.
Schaerer-Brodbeck
Claudia
C
University of Geneva, Department of Biochemistry, Sciences II, 30, quai E. Ansermet, 1211 Geneva 4, Switzerland.
Riezman
Howard
H
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000235:genetics / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D047390:Casein Kinase II; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014404:Tubulin / Q000235:genetics / Q000378:metabolism*
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; D002147:Calmodulin; D003598:Cytoskeletal Proteins; D029701:Saccharomyces cerevisiae Proteins; C100764:TUB4 protein, S cerevisiae; D014404:Tubulin; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases