Pak1 Protein Kinase Regulates Activation and Nuclear Localization of Snf1-Gal83 Protein Kinase
AUTOR(ES)
Hedbacker, Kristina
FONTE
American Society for Microbiology
RESUMO
Three kinases, Pak1, Tos3, and Elm1, activate Snf1 protein kinase in Saccharomyces cerevisiae. This cascade is conserved in mammals, where LKB1 activates AMP-activated protein kinase. We address the specificity of the activating kinases for the three forms of Snf1 protein kinase containing the β-subunit isoforms Gal83, Sip1, and Sip2. Pak1 is the most important kinase for activating Snf1-Gal83 in response to glucose limitation, but Elm1 also has a significant role; moreover, both Pak1 and Elm1 affect Snf1-Sip2. These findings exclude the possibility of a one-to-one correspondence between the activating kinases and the Snf1 complexes. We further identify a second, unexpected role for Pak1 in regulating Snf1-Gal83: the catalytic activity of Pak1 is required for the nuclear enrichment of Snf1-Gal83 in response to carbon stress. The nuclear enrichment of Snf1 fused to green fluorescent protein (GFP) depends on both Gal83 and Pak1 and is abolished by a mutation of the activation loop threonine; in contrast, the nuclear enrichment of Gal83-GFP occurs in a snf1Δ mutant and depends on Pak1 only when Snf1 is present. Snf1-Gal83 is the only form of the kinase that localizes to the nucleus. These findings, that Pak1 both activates Snf1-Gal83 and controls its nuclear localization, implicate Pak1 in regulating nuclear Snf1 protein kinase activity.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=515071Documentos Relacionados
- Yeast Pak1 Kinase Associates with and Activates Snf1
- Dissecting Activation of the PAK1 Kinase at Protrusions in Living Cells*
- Cyclic AMP-Dependent Protein Kinase Regulates the Subcellular Localization of Snf1-Sip1 Protein Kinase
- The Snf1 protein kinase and its activating subunit, Snf4, interact with distinct domains of the Sip1/Sip2/Gal83 component in the kinase complex.
- Mutations in the Gal83 Glycogen-Binding Domain Activate the Snf1/Gal83 Kinase Pathway by a Glycogen-Independent Mechanism
