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Ana Kitazono F225 Walters Life Sciences |
Keywords:
Cell cycle regulation; mitosis, checkpoints; cyclin-dependent kinases
Research Area:
Regulation of mitosis by the Cdc28 cyclin-dependent kinase (CDK); Cdc28 (Cdc2/Cdk1) phosphorylates specific substrates
Description of Research:
How do cells regulate their growth and division? What are the molecular mechanisms behind this regulation? What happens when these mechanisms are not working properly? These are the main questions that motivate our research, using the bakers’ yeast Saccharomyces cerevisiae. This system allows us to employ a wide array of genetic, cell biological and biochemical techniques, taking advantage of the abundant resources available (markers for selection, variety of vectors and inducible promoters, genome databases, genomic DNA libraries for expression and to perform genetic screens, libraries for genomic and proteomic studies, etc.). Further, since most cell cycle mechanisms are remarkably conserved, findings in yeast are relevant towards understanding how human cells regulate their growth.
Currently, we are focusing our studies in the regulation of mitosis by the Cdc28 cyclin-dependent kinase (CDK), the main regulator of the yeast cell cycle. Cdc28 (Cdc2/Cdk1) phosphorylates specific substrates in a timely manner and requires for activity binding of different cyclin subunits, which determine the specificity and localization of the complexes. Activation of Cdc28 also requires phosphorylation by the Cak1 kinase and binding of the Cks1 subunit. We found that mutations at the carboxyl-terminus of Cdc28 result in inappropriate mitotic progression and high levels of chromosome instability. Interestingly, presence of high copy numbers of Cak1 suppresses these phenotypes independently of its catalytic activity, suggesting that the carboxyl-terminus of Cdc28 is essential for binding. We are currently analyzing the nature of this interaction and its effect on Cdc28 activity and the regulation of mitotic progression.
Selected Publications:
- Kitazono AA and Kron SJ (2004) The CDK-activating kinase Cak1 promotes chromosome stability in yeast by stabilizing Cdc28/Cdk1 complexes during mitosis. J. Biol. Chem. (under revision)
- Kitazono A, Garza D and Kron S. (2003) Spindle checkpoint deficiency and chromosome instability in budding yeast cyclin-dependent kinase mutants. Mol.Gen. Genomics 269: 672-684. PubMed
- Kitazono A, Gerald JF and Kron S (2003 and 2000) Cell cycle: Regulation by cyclins. Encyclopedia of Life Sciences, Stockton Press. Nature ELS
- Kitazono AA, Ito K and Yoshimoto T (2003) Prolyl aminopeptidase in Handbook of Proteolytic Enzymes, Academic Press.
- Kitazono AA and Kron SJ (2002) An Essential Function of Yeast Cyclin-dependent Kinase Cdc28 Maintains Chromosome Stability. J. Biol. Chem. 277: 48627-48634. PubMed
- Kitazono AA, Tobe BTD, Kalton H, Diamant N and Kron SJ (2002) Marker-fusion PCR for one-step mutagenesis of essential genes in yeast. Yeast 19: 141-149. PubMed
- Kitazono A and Matsumoto T (1998) "Isogaba Maware": Quality control of genome DNA by checkpoints. BioEssays 20: 391-399. PubMed
- Kim S, Lin D, Matsumoto S, Kitazono A and Matsumoto T (1997) Fission yeast Slp1: An effector of the Mad2-dependent checkpoint. Science 279: 1045-1048. PubMed
- Kabashima T, Kitazono A, Kitano A, Ito K and Yoshimoto T. (1997) Prolyl aminopeptidase from Serratia marcescens: Sequencing and expression of the enzyme gene and crystallization of the expressed enzyme. J. Biochem. 122: 601-605. PubMed
- Kitazono A, Kitano A, Kabashima T, Ito K and Yoshimoto T (1996) Prolyl Aminopeptidase Is Also Present in Enterobacteriaceae: Cloning and Sequencing of the Hafnia alvei Enzyme-Gene and Characterization of the Expressed Enzyme. J. Biochem. 119: 468-474. PubMed
- Kitazono A, Kabashima T, Huang H, Ito K and Yoshimoto T (1996) Prolyl aminopeptidase-gene from Flavobacterium meningosepticum: Cloning, purification of the expressed enzyme and analysis of its sequenc. Arch. Biochem. Biophys. 336: 35-41. PubMed