Temperature-sensitive Mutations of the CKA1 Gene Reveal a Role for Casein Kinase II in Maintenance of Cell Polarity in Saccharomyces cerevisiae

Abstract

Casein kinase II (CKII) of Saccharomyces cerevisiae contains two distinct catalytic subunits, ␣ and ␣, that are encoded by the CKA1 and -2 genes, respectively. We have constructed conditional alleles of the CKA1 gene. In contrast to cka1 cka2 ts strains, which exhibit a defect in both G 1 and G 2 /M cell cycle progression, cka1 ts cka2 strains continue to divide for three cell cycles after a shift to restrictive temperature and then arrest as a mixture of budded and unbudded cells with a spherical morphology. Arrested cells exhibit continued growth, a nonpolarized actin cytoskeleton, delocalized chitin deposition, and a significant fraction of multinucleate cell bodies, confirming the presence of a cell polarity defect in cka1 ts strains. The presence of budded as well as unbudded cells in the arrested population suggests that CKII is required for maintenance rather than establishment of cell polarity, although a role in both processes is also possible. The terminal phenotype of cka1 ts strains bears a strong resemblance to that of orb5 strains of Schizosaccharomyces pombe, which carry a temperature-sensitive CKII catalytic subunit mutation, but the underlying mechanism appears to be different in the two cases. These results establish a requirement for CKII in cell polarity in S. cerevisiae and provide the first evidence for functional specialization of CKA1 and -2.

Protein kinase CK2 regulates CDC25B phosphatase activity

“…The activity was normalized to CDC25B3 quantity detected in Western-blot and expressed as a fold activation compared to CDC25B3 activity detected in the simple infection. These results are representative of four independent experiments CK2 regulates CDC25B phosphatase activity N Theis-Febvre et al M phases (Mulner-Lorillon et al, 1988;Padmanabha et al, 1990;Hanna et al, 1995;Rethinaswamy et al, 1998). In this study, we have shown that, in vitro, CK2 kinase phosphorylates specifically one of the two CDC25 phosphatases implicated in the regulation of the G2/M transition.…”

Identification and Characterization of CKIP-1, a Novel Pleckstrin Homology Domain-containing Protein That Interacts with Protein Kinase CK2

“…Interestingly, likely physiological targets for CK2 include a number of proteins that regulate intracellular trafficking such as p65 (synaptotagmin) (72), furin (73,74), and dynein (75). The observations that CK2␣ is implicated in the polarized growth of both fission and budding yeast cells (76,77), as well as neuritogenesis in mouse neuroblastoma (N2A) cells (78), also suggests a role for CK2 in the organization of the actin cytoskeleton. In fact, many proteins that interact with the cytoskeletal regulating GTPases (Rac, Rho, and cdc42) possess PH domains, leucine zippers, prolinerich regions, and/or kinase domains (79).…”

Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi

“…Additionally, several microtubule-associated proteins (MAPs) seem to be involved in interconnecting microtubules to each other, as well as to the plasma membrane (Gull 1999). Previous reports have suggested that CK2 plays an important role in the maintenance of cell morphology and polarity (Ulloa et al 1994, Rethinaswamy et al 1998. Also, coimmunoprecipitation and in vitro binding studies have evidenced that CK2 is strongly associated to tubulin in mammalian cell extracts (Faust et al 1999).…”