Differential stabilities of phosphorylated response regulator domains reflect functional roles of the yeast osmoregulatory SLN1 and SSK1 proteins.
Osmoregulation in Saccharomyces cerevisiae involves a multistep phosphorelay system requiring three proteins, SLN1, YPD1, and SSK1, that are related to bacterial two-component signaling proteins, in particular, those involved in regulating sporulation in Bacillus subtilis and anaerobic respiration in Escherichia coli. The SLN1-YPD1-SSK1 phosphorelay regulates a downstream mitogen-activated protein kinase cascade which ultimately controls the concentration of glycerol within the cell under hyperosmotic stress conditions. The C-terminal response regulator domains of SLN1 and SSK1 and full-length YPD1 have been overexpressed and purified from E. coli. A heterologous system consisting of acetyl phosphate, the bacterial chemotaxis response regulator CheY, and YPD1 has been developed as an efficient means of phosphorylating SLN1 and SSK1 in vitro. The homologous regulatory domains of SLN1 and SSK1 exhibit remarkably different phosphorylated half-lives, a finding that provides insight into the distinct roles that these phosphorylation-dependent regulatory domains play in the yeast osmosensory signal transduction pathway.
Janiak-Spens
F
F
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA.
Sparling
J M
JM
Gurfinkel
M
M
West
A H
AH
D001426:Bacterial Proteins; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D010755:Organophosphates / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D010755:Organophosphates; D011994:Recombinant Proteins; C087199:SSK1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C000607606:cheY protein, E coli; C011632:acetyl phosphate; D011494:Protein Kinases; C102035:YPD1 protein, S cerevisiae; C083749:SLN1 protein, S cerevisiae