Disease relevance of BCY1

• Expression in Escherichia coli of BCY1, the regulatory subunit of cyclic AMP-dependent protein kinase from Saccharomyces cerevisiae. Purification and characterization [1].
• The regulatory (R) subunit of cAMP-dependent protein kinase from the yeast Saccharomyces cerevisiae was expressed in Escherichia coli by engineering the gene for yeast R, BCY1, into an E. coli expression vector that contained a promoter from phage T7 [1].
• Considering the degree of autolysis, ethanol tolerance, and technical feasibility, we propose that deletion of the 3' end of the open reading frame of a single copy of BCY1 is a way to improve the quality of sparkling wines [2].

High impact information on BCY1

• We have isolated mutant TPK genes that suppress all of the bcy1- defects [3].
• S. cerevisiae strains containing RAS2val19, a RAS2 gene with a missense mutation analogous to one that activates the transforming potential of mammalian ras genes, have growth and biochemical properties strikingly similar to yeast strains carrying IAC or bcy1 [4].
• Yeast strains carrying the IAC mutation have elevated levels of adenylate cyclase activity. bcy1 is a mutation that suppresses the lethality in adenylate cyclase deficient yeast [4].
• In diploids homozygous for the bcy1 mutation that results in deficiency of the regulatory subunit of cAMP-dependent protein kinase and production of a high level of the catalytic subunit of this enzyme, no premeiotic DNA replication and commitment to intragenic recombination occurred, and no spores were formed [5].
• A strain with a mutation in the regulatory subunit of the cAMP-dependent protein kinase (bcy1) fails to accumulate GPH1 and GAC1 RNA [6].

Biological context of BCY1

• The cellular level of C1 was increased by expressing the genes for C1 (TPK1) and yeast regulatory subunit (BCY1) on multiple copy plasmids within this strain [7].
• In contrast, a mutation in RAS2 (RAS2val19) which increases the level of cAMP or a mutation in the regulatory subunit (BCY1) of cAMP-dependent protein kinase which results in unregulated cAMP-dependent protein kinase activity accentuates the snf1 phenotype [8].
• Spontaneous mutations in the gene which encodes the regulatory subunit of cAMP-dependent protein kinase (PKA) of Saccharomyces cerevisiae (BCY1) have been isolated previously [Cannon, J. F., Gibbs, J. B. & Tatchell, K. (1986) Genetics 113, 247-264] by selection of ras2::LEU2 revertants that grew on non-fermentable carbon sources [9].
• The presence in a bcy1 diploid of IME1 multicopy plasmids does not cure the failure of bcy1 cells to arrest as unbudded cells following starvation and to enter the G0 state (thermotolerance, synthesis of unique G0 proteins) [10].
• We cloned SRA1 and SRA3 and determined their DNA sequences [11].

Anatomical context of BCY1

• Remarkably, Zds1 appears to act as a negative regulator of cell wall integrity signaling, and this activity is dependent in part on the phosphorylation status of Bcy1 [12].
• Furthermore, the treatment of membranes with cAMP or dibutyryl cAMP caused the activation of PI kinase in wild type, ras1, cry1-2, and ras2 strains, but not in bcy1 strain cells [13].
• By using photoaffinity labeling with 8-N3-[32P]cAMP, we have identified in plasma membrane vesicles a cAMP-binding protein (Mr = 54,000) that is present also in bcy1 disruption mutants, lacking the cytoplasmic R subunit of protein kinase A (PKA) [14].

Associations of BCY1 with chemical compounds

• Yeast transformants containing increased kinase activity resulting from overexpression of RAS2Val19 or TPK1 and yeast strains having increased kinase activities due to mutations in the BCY1 gene also did not show alterations in their sensitivity to cisplatin [15].
• In the bcy1 tpk2 mutant, protein kinase A activity (due to the presence of the TPK1 gene) was cyclic AMP independent, indicating that the cells harbored an unregulated phosphotransferase activity [16].
• The morphogenetic behavior of several C. albicans mutant strains bearing one or both BCY1 alleles, in a wild-type and in a TPK2 null genetic background, was assessed in N-acetylglucosamine (GlcNAc) liquid medium at 37 degrees C. Strains with one BCY1 allele tagged or not, behaved similarly, displaying pseudohyphae and true hyphae [17].
• In glucose-grown cells, Bcy1 is almost exclusively nuclear, while it appears more evenly distributed between nucleus and cytoplasm in carbon source-derepressed cells [18].
• Site-directed mutagenesis of two clusters (I and II) of serines near the N terminus to alanine resulted in an enhanced nuclear accumulation of Bcy1 in ethanol-grown cells [18].

Physical interactions of BCY1

• We show that different sequences of Reg1 interact with Glc7 and Snf1 [19].

Enzymatic interactions of BCY1

• The reduced phosphatidylserine synthase activity in the bcy1 mutant correlated with elevated levels of a phosphorylated form of the phosphatidylserine synthase Mr 23,000 subunit [20].

Regulatory relationships of BCY1

• In addition, we have identified a polymorphic gene, SSD1, that in some versions can suppress the lethality due to a deletion of SIT4 and can also partially suppress the phenotypic defects due to a null mutation in BCY1 [21].
• Furthermore, a deficiency of the cAMP-binding regulatory subunit (RA) caused by the bcy1 mutation fails to suppress the cdc25 mutation, indicating that PK-25 does not interact with the cAMP receptor protein [22].
• The multicopy MSI2 also suppresses the heat shock sensitivity of cells with the RAS2val19 mutation but not those with the bcy1 mutation, suggesting that the MSI2 protein may interfere with the activity of the RAS protein [23].
• In Saccharomyces cerevisiae, the unregulated cyclic AMP-dependent protein kinase (cAPK) activity of bcy1 mutant cells inhibits expression of the glucose-repressible ADH2 gene [24].
• Previous studies showed that Reg1 regulates the Snf1 protein kinase in response to glucose [19].

Other interactions of BCY1

• Multicopy IME1 plasmids overcome the meiotic deficiency of bcy1 and of RASval19 diploids [10].
• Some sra1 and SRA4 and all SRA3 mutations were RAS independent, allowing growth of yeast cells that lack a functional RAS gene [25].
• Overexpression of the high-affinity cAMP phosphodiesterase gene (PDE2) in the bcy1 ras2::LEU2 strains did not alter their PKA-dependent phenotypes [9].
• Moreover, BCY1 overexpression not only increased Tpk3 catalytic activity but also increased the amount of TPK3 mRNA detected in Northern blots [26].
• Constitutive PKA activity caused by mutation of the negative regulator BCY1 is toxic to DASH mutants such as ask1 and dam1 [27].

Analytical, diagnostic and therapeutic context of BCY1

• The presence of PKA in both fractions was confirmed by immunoblotting with anti-Bcy1 antibodies [28].
• The isoforms observed by one-dimensional SDS-PAGE bind cAMP, as determined by [32P]8-azido-cAMP labeling (diagnostic of Bcy1 protein) [29].
• The subcellular distribution of the regulatory subunit of cAMP-dependent protein kinase in Saccharomyces cerevisiae cells was determined by subcellular fractionation and indirect immunofluorescence microscopy using the bcy1 mutant deficient in the regulatory subunit as control [30].
• Mutants lacking the serotype A protein kinase A (PKA) catalytic subunit Pka1 are unable to mate, fail to produce melanin or capsule, and are avirulent in animal models, whereas mutants lacking the PKA regulatory subunit Pkr1 overproduce capsule and are hypervirulent [31].
• Yeast two-hybrid analysis and co-immunoprecipitation studies showed that AKAP7gamma bound the type I PKA regulatory subunit (RI) and that the RI-binding domain overlapped the previously identified type II PKA regulatory subunit (RII) binding domain [32].

References