Phosphorylation of Mcm2 Protein by Cdc7 Kinase Is Not Essential for the Initiation of DNA Replication in Fission Yeast

다국어 초록 (Multilingual Abstract)

Previous studies in many species suggested that the minichromosome maintenance complex
is a major physiological target of Cdc7. In this study, we examined the cellular role of Mcm2
phosphorylation by Cdc7 kinase in Schizosaccharomyces pombe. The in vitro phosphorylation
of several truncated Mcm2 proteins by Cdc7 kinase showed that the major phosphorylation
sites were located at N-terminus of Mcm2 protein. Alanine substitutions of several putative
Cdc7 phosphorylation sites in this region resulted in the mutant Mcm2 proteins which were
hardly phosphorylated by Cdc7 kinase in vitro. When these proteins were expressed in mcm2
mutant cells, all of alanine substituted mutant proteins still complemented the temperature
sensitive phenotype of mutant cells. These results suggest that the phosphorylation of Mcm2
protein by Cdc7 kinase is not essential for the initiation of DNA replication. Cdc7 may play
its essential roles by phosphorylating other Mcm subunits or proteins involved in the initiation
of DNA replication.

다국어 초록 (Multilingual Abstract)

Previous studies in many species suggested that the minichromosome maintenance complex
is a major physiological target of Cdc7. In this study, we examined the cellular role of Mcm2
phosphorylation by Cdc7 kinase in Schizosaccharomyces pombe. The in vitro phosphorylation
of several truncated Mcm2 proteins by Cdc7 kinase showed that the major phosphorylation
sites were located at N-terminus of Mcm2 protein. Alanine substitutions of several putative
Cdc7 phosphorylation sites in this region resulted in the mutant Mcm2 proteins which were
hardly phosphorylated by Cdc7 kinase in vitro. When these proteins were expressed in mcm2
mutant cells, all of alanine substituted mutant proteins still complemented the temperature
sensitive phenotype of mutant cells. These results suggest that the phosphorylation of Mcm2
protein by Cdc7 kinase is not essential for the initiation of DNA replication. Cdc7 may play
its essential roles by phosphorylating other Mcm subunits or proteins involved in the initiation
of DNA replication.

참고문헌 (Reference)

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