N-Terminal Mutations Modulate Yeast Snf1 Protein Kinase Function

AUTOR(ES)

Estruch, F.

RESUMO

The SNF1 protein kinase is required for expression of glucose-repressed genes in response to glucose deprivation. The SNF4 protein is physically associated with SNF1 and positively affects the kinase activity. We report here the characterization of a dominant mutation, SNF1-G53R, that was isolated as a suppressor of the requirement for SNF4. The mutant SNF1-G53R protein is still responsive to SNF4 but has greatly elevated kinase activity in immune complex assays; in contrast, the activity is wild type in a protein blot assay. Deletion of the region N-terminal to the kinase domain (codons 5-52) reduces kinase activity in vitro, but the mutant SNF1-ΔN kinase is still dependent on SNF4. The N terminus is not required for the regulatory response to glucose. In gel filtration chromatography, the SNF1, SNF1-G53R and SNF1-ΔN proteins showed different elution profiles, consistent with differential formation of high molecular weight complexes. Taken together, the results suggest that the N terminus positively affects the function of the SNF1 kinase and may be involved in interaction with a positive effector other than SNF4. We also showed that the conserved threonine residue 210 in subdomain VIII, which is a phosphorylation site in other kinases, is essential for SNF1 activity. Finally, we present evidence that when the C terminus is deleted, overexpression of the SNF1 kinase domain is deleterious to the cell.

Documentos Relacionados

• The N-terminal to C-terminal motif in protein folding and function
• Histone H3 N-terminal mutations allow hyperactivation of the yeast GAL1 gene in vivo.
• Yeast Pak1 Kinase Associates with and Activates Snf1
• Activation of yeast Snf1 and mammalian AMP-activated protein kinase by upstream kinases
• Phosphorylated Tau Interacts with c-Jun N-terminal Kinase-interacting Protein 1 (JIP1) in Alzheimer Disease*