Identification of stimulators and inhibitors of Cdc7 kinase in vitro.
Cdc7 is a serine-threonine kinase that regulates initiation and progression of DNA replication. The activity of purified Cdc7 kinase is significantly stimulated by polyamines such as spermine or spermidine. Positively charged polymers of lysine or arginine also stimulate its kinase activity, whereas the negatively charged substances such as polyglutamate or nucleic acids significantly inhibit the kinase activity. Spermine affects both the K(m) and V(max) of Cdc7 kinase for a minichromosome maintenance (MCM) substrate. We also found that histones, lysine- and arginine-rich basic proteins, can stimulate Cdc7 kinase activity, and a MCM complex in association with histone is a more efficient substrate of Cdc7 than the free MCM complex. These results identify potential cellular inhibitors and stimulators of Cdc7 kinase and suggest that Cdc7 may be another target of cellular polyamines and that histones may stimulate Cdc7-mediated phosphorylation of chromatin-bound substrates. Ectopic expression of an antizyme, known to reduce the cellular polyamine levels, resulted in reduction of Cdc7-mediated phosphorylation of MCM4 protein, suggesting physiological roles of polyamines in regulation of Cdc7 kinase activity in the cells.
Kakusho
Naoko
N
Genome Dynamics Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 113-8613, Japan.
Taniyama
Chika
C
Masai
Hisao
H
D000818:Animals; D015317:Biogenic Polyamines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006657:Histones / Q000378:metabolism; D006801:Humans; D064148:Minichromosome Maintenance Complex Component 4; D009097:Multienzyme Complexes / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000099272:Replisomes
D015317:Biogenic Polyamines; D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D020536:Enzyme Activators; D006657:Histones; D064148:Minichromosome Maintenance Complex Component 4; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D000099272:Replisomes; C068619:CDC7 protein, human; C099243:MCM4 protein, human