Xenopus cyclin A1 can associate with Cdc28 in budding yeast, causing cell-cycle arrest with an abnormal distribution of nuclear DNA.
BACKGROUND
Cyclins play a regulatory role in cell cycle progression, associated with cyclin-dependent kinases. We have investigated the structure-function relationships of cyclin A, mainly using Xenopus egg extracts in vitro. To further analyse the function and structure of cyclin A in vivo, we expressed Xenopus cyclin A1 in the budding yeast Saccharomyces cerevisiae.


RESULTS
We herein show that vertebrate cyclin A1 can associate with endogenous Cdc28 to form histone H1 kinase. The growth of the yeast was inhibited by the expression of indestructible cyclin A1, but not by a non-Cdk binding cyclin A1 mutant. The induction of cyclin A1 expression in yeast caused cell cycle arrest with an abnormal distribution of nuclear DNA to the daughter bud. Suppressors of the cyclin A1-mediated growth arrest were identified as new alleles of the cdc28 mutation that reduced the binding of cyclin A1 and possessed different affinities for the cyclin-Cdc28 complexes. The temperature-sensitivity of the cdc28 mutation was thus preferentially suppressed by the endogenous cyclins CLN2 and CLB2.


CONCLUSIONS
These results suggest that the Cdc28 protein kinase activity mediated by vertebrate cyclin A1 may be involved in the process of nuclear movement in the yeast, and thereby affect the dependence of the M phase on the completion of the S phase through a preferential binding affinity of the cyclin-Cdc28 complex.
Funakoshi
M
M
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
Sikder
H
H
Ebihara
H
H
Irie
K
K
Sugimoto
K
K
Matsumoto
K
K
Hunt
T
T
Nishimoto
T
T
Kobayashi
H
H
D000595:Amino Acid Sequence; D000818:Animals; D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D019925:Cyclin A; D016213:Cyclins / Q000378:metabolism*; D004271:DNA, Fungal / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D011494:Protein Kinases / Q000096:biosynthesis; D016196:S Phase; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic; D014981:Xenopus
D019925:Cyclin A; D016213:Cyclins; D004271:DNA, Fungal; D005656:Fungal Proteins; D011494:Protein Kinases; C102333:histone H1 kinase; D017489:CDC28 Protein Kinase, S cerevisiae