Cdc37 is required for association of the protein kinase Cdc28 with G1 and mitotic cyclins.

Abstract

Studies of the temperature-sensitive cdc37-1 mutant of Saccharomyces cerevisiae suggest that Cdc37 is required for passage through the G1 phase of the cell cycle, but its precise function is not known. We have investigated the role of Cdc37 in the regulation of the cyclin-dependent protein kinase Cdc28. We find that G1 arrest in the cdc37-1 mutant is accompanied by a decrease in the Cdc28 activity associated with the G1 cyclin Cln2 (3,4). Mutations in CDC36 and CDC39 result in constitutive activation of the mating pheromone pathway (5), whereas CDC28 is more directly involved in cell cycle control (1, 2, 6).The function of CDC37 is unknown.The product of the CDC28 gene is a member of the highly conserved family of cyclin-dependent kinases (CDKs), whose activation at specific cell cycle stages requires association with cyclin regulatory subunits (2,(7)(8)(9). The commitment to a new cell division cycle in G1 is controlled by complexes of Cdc28 and the G1 cyclins Clnl, -2, and -3. G1 arrest by mating pheromone involves inhibition of specific Cdc28-Cln complexes and decreased synthesis of Clnl and Cln2. Cdc28 function is also required later in the cell cycle: progress through S phase and mitosis requires activation of Cdc28 by S-phase cyclins (Clb5 and -6) and mitotic cyclins (Clbl, -2, -3, and -4), respectively (see ref For a-factor arrest, 120-ml cultures were grown at 24°C to an OD600 of 0.5. a-Factor (1.0 tLg/ml) was added for 2 hr. For mitotic arrest, 25-ml cultures were grown at 24°C to an OD600 of 0.3. Cells were transferred to medium containing benomyl (60 ,ug/ml) and nocodazole (20 ,g/ml) for 2 hr at 24°C.A 5.8-kb genomic DNA fragment containing the CDC37 gene was a gift of S. Reed (Scripps Institute, La Jolla, CA). To construct the cdc37A allele, a fragment of CDC37 (coding for aa Figs. 1-3, logarithmic-phase cells were resuspended in 700 ptl of ice-cold 20 mM Tris-HCl, pH 7.4/0.1% Triton X-100/100 mM NaCl/5 mM EDTA/50 mM P-glycerophosphate/50 mM NaF/1 mM phenylmethylsulfonyl fluoride/1 mM dithiothreitol with aprotinin (2 ,tg/ml) and leupeptin (1 tLg/ml). One milliliter of glass beads was added, and cells were lysed at 4°C by two pulses (60 s) in a miniBeadBeater (Biospec Products, Bartlesville, OK). Lysates were clarified by centrifugation at 14,000 x g for 10 min at 4°C. In Fig. 4

Fungal Hsp90: a biological transistor that tunes cellular outputs to thermal inputs

“…In S. cerevisiae, the Hsp90 co-chaperone Cdc37, as well as Hsp90 itself modulates the function of the crucial cell cycle regulator, Cdc28 61,113 . Furthermore, in C. albicans, this cyclin-dependent kinase interacts physically with, and is stabilized by Hsp90 114 .…”

Organization of the Chick CDC37 Gene

“…Genetic studies have shown CDC37 is essential for the START event in yeast (1,2), but other studies have shown that CDC37 is probably required in G 2 /M as well as G 1 (3,4). Vertebrate CDC37 has been cloned from several species (5)(6)(7)(8), and, recently, it was shown to be identical to p50 (8,9).…”

Identification of a Conserved Sequence Motif That Promotes Cdc37 and Cyclin D1 Binding to Cdk4

“…Yeast strains with temperature-sensitive alleles of CDC37 (cdc37-1 or cdc37-34) arrest in late G 1 or in G 2 /M (2, 3). Subsequent studies indicated that cdc37-1 confers a defect in the binding and activation of the yeast cyclin-dependent kinase Cdc28 by the G 1 cyclin Cln2 or the G 2 /M cyclin Clb2 (4). Genetic and biochemical evidence has suggested Cdc37 interacts with other protein kinases in yeast, including casein kinase II (5), Ste11 (6), Kin28 (7), and Mps1 (8), and is important for the stability and activity of these protein kinases.…”