Casein kinase II is required for cell cycle progression during G1 and G2/M in Saccharomyces cerevisiae.
The catalytic subunit of Saccharomyces cerevisiae casein kinase II (Sc CKII) is encoded by the CKA1 and CKA2 genes, which together are essential for viability. Five independent temperature-sensitive alleles of the CKA2 gene were isolated and used to analyze the function of CKII during the cell cycle. Following a shift to the nonpermissive temperature, cka2ts strains arrested within a single cell cycle and exhibited a dual arrest phenotype consisting of 50% unbudded and 50% large-budded cells. The unbudded half of the arrested population contained a single nucleus and a single focus of microtubule staining, consistent with arrest in G1. Most of the large-budded fraction contained segregated chromatin and an extended spindle, indicative of arrest in anaphase, though a fraction contained an undivided nucleus with a short thick intranuclear spindle, indicative of arrest in G2 and/or metaphase. Flow cytometry of pheromone-synchronized cells confirmed that CKII is required in G1, at a point which must lie at or beyond Start but prior to DNA synthesis. Similar analysis of hydroxyurea-synchronized cells indicated that CKII is not required for completion of previously initiated DNA replication but confirmed that the enzyme is again required for cell cycle progression in G2 and/or mitosis. These results establish a role for CKII in regulation and/or execution of the eukaryotic cell cycle.
Hanna
D E
DE
Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602-7229, USA.
Rethinaswamy
A
A
Glover
C V
CV
D001483:Base Sequence; D047390:Casein Kinase II; D002453:Cell Cycle; D002467:Cell Nucleus / Q000648:ultrastructure; D003599:Cytoskeleton / Q000648:ultrastructure; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000096:biosynthesis; D016193:G1 Phase; D016195:G2 Phase; D006918:Hydroxyurea / Q000494:pharmacology; D008938:Mitosis; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D017422:Sequence Analysis, DNA
D005656:Fungal Proteins; D012331:RNA, Fungal; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D006918:Hydroxyurea