Regulation of maltose utilization in Saccharomyces cerevisiae
 by genes of the RAS/protein kinase A pathway
1

ABSTRACT Pak5 is the most recently identified and least understood member of the p21-activated kinase (Pak) family. This kinase is known to promote neurite outgrowth in vitro, but its localization, substrates, and effects on cell survival have not been reported. We show here that Pak5 has unique properties that distinguish it from all other members of the Pak family. First, Pak5, unlike Pak1, cannot complement an STE20 mutation in Saccharomyces cerevisiae. Second, Pak5 binds to the GTPases Cdc42 and Rac, but these GTPases do not regulate Pak5 kinase activity, which is constitutive and stronger than any other Pak. Third, Pak5 prevents apoptosis induced by camptothecin and C2-ceramide by phosphorylating BAD on Ser-112 in a protein kinase A-independent manner and prevents the localization of BAD to mitochondria, thereby inhibiting the apoptotic cascade that leads to apoptosis. Finally, we show that Pak5 itself is constitutively localized to mitochondria, and that this localization is independent of kinase activity or Cdc42 binding. These features make Pak5 unique among the Pak family and suggest that it plays an important role in apoptosis through BAD phosphorylation.

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Transcriptional regulation of the protein kinase A subunits in Saccharomyces cerevisiae: Autoregulatory role of the kinase A activity

Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms ◽

10.1016/j.bbagrm.2014.02.005 ◽

2014 ◽

Vol 1839 (4) ◽

pp. 275-287 ◽

Cited By ~ 6

Author(s):

Constanza Pautasso ◽

Silvia Rossi

Keyword(s):

Saccharomyces Cerevisiae ◽

Transcriptional Regulation ◽

Protein Kinase ◽

Protein Kinase A ◽

Kinase A

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Genetic Analysis of the Kinetochore DASH Complex Reveals an Antagonistic Relationship with the Ras/Protein Kinase A Pathway and a Novel Subunit Required for Ask1 Association

Molecular and Cellular Biology ◽

10.1128/mcb.25.2.767-778.2005 ◽

2005 ◽

Vol 25 (2) ◽

pp. 767-778 ◽

Cited By ~ 25

Author(s):

Ju-mei Li ◽

Yumei Li ◽

Stephen J. Elledge

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Chromosome Segregation ◽

Biochemical Analysis ◽

Genetic Interaction ◽

Negative Regulator ◽

Ras Protein ◽

Sister Chromatids ◽

Pka Pathway ◽

Kinase A

ABSTRACT DASH is a microtubule- and kinetochore-associated complex required for proper chromosome segregation and bipolar attachment of sister chromatids on the mitotic spindle. We have undertaken a genetic and biochemical analysis of the DASH complex and uncovered a strong genetic interaction of DASH with the Ras/protein kinase A (PKA) pathway. Overexpression of PDE2 or deletion of RAS2 rescued the temperature sensitivity of ask1-3 mutants. Ras2 negatively regulates DASH through the PKA pathway. Constitutive PKA activity caused by mutation of the negative regulator BCY1 is toxic to DASH mutants such as ask1 and dam1. In addition, we have discovered two novel subunits of DASH, Hsk2 and Hsk3 (helper of Ask1), which are microproteins of fewer than 75 amino acids, as dosage suppressors of ask1 mutants. These are essential genes that colocalize with DASH components on spindles and kinetochores and are present in the DASH complex. Mutants in hsk3 arrest cells in mitosis with short spindles and broken spindle structures characteristic of other DASH mutants. Hsk3 is critical for the integrity of the DASH complex because in hsk3 mutants the association of Dam1, Duo1, Spc34, and Spc19 with Ask1 is greatly diminished. We propose that Hsk3 acts to incorporate Ask1 into the DASH complex.

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