Molecular characterization ofArabidopsisPHO80-like proteins, a novel class of CDKA;1-interacting cyclins
ABSTRACT Cyclins are regulatory proteins that interact with cyclin-dependent kinases (CDKs) to control progression through the cell cycle. In Arabidopsis thaliana, 34 cyclin genes have been described, grouped into five different types (A, B, D, H, and T). A novel class of seven cyclins was isolated and characterized in Arabidopsis, designated P-type cyclins (CYCPs). They all share a conserved central region of 100 amino acids (cyclin box) displaying homology to the corresponding region of the PHO80 cyclin from Saccharomyces cerevisiae and the related G1 cyclins from Trypanosoma cruzi and T. brucei. The CYCP4;2 gene was able to partially re-establish the phosphate-dependent expression of the PHO5 gene in a pho80 mutant strain of yeast. The CYCPs interact preferentially with CDKA;1 in vivo and in vitro as shown by yeast two-hybrid analysis and co-immunoprecipitation experiments. P-type cyclins were mostly expressed in proliferating cells, albeit also in differentiating and mature tissues. The possible role of CYCPs in linking cell division, cell differentiation, and the nutritional status of the cell is discussed.
Article: A cotton-fiber-associated cyclin-dependent kinase a gene: characterization and chromosomal location.[show abstract] [hide abstract]
ABSTRACT: A cotton fiber cDNA and its genomic sequences encoding an A-type cyclin-dependent kinase (GhCDKA) were cloned and characterized. The encoded GhCDKA protein contains the conserved cyclin-binding, ATP binding, and catalytic domains. Northern blot and RT-PCR analysis revealed that the GhCDKA transcript was high in 5-10 DPA fibers, moderate in 15 and 20 DPA fibers and roots, and low in flowers and leaves. GhCDKA protein levels in fibers increased from 5-15 DPA, peaked at 15 DPA, and decreased from 15 t0 20 DPA. The differential expression of GhCDKA suggested that the gene might play an important role in fiber development. The GhCDKA sequence data was used to develop single nucleotide polymorphism (SNP) markers specific for the CDKA gene in cotton. A primer specific to one of the SNPs was used to locate the CDKA gene to chromosome 16 by deletion analysis using a series of hypoaneuploid interspecific hybrids.International Journal of Plant Genomics 01/2012; 2012:613812.
Article: Genome-wide analysis of the diatom cell cycle unveils a novel type of cyclins involved in environmental signaling.[show abstract] [hide abstract]
ABSTRACT: Despite the enormous importance of diatoms in aquatic ecosystems and their broad industrial potential, little is known about their life cycle control. Diatoms typically inhabit rapidly changing and unstable environments, suggesting that cell cycle regulation in diatoms must have evolved to adequately integrate various environmental signals. The recent genome sequencing of Thalassiosira pseudonana and Phaeodactylum tricornutum allows us to explore the molecular conservation of cell cycle regulation in diatoms. By profile-based annotation of cell cycle genes, counterparts of conserved as well as new regulators were identified in T. pseudonana and P. tricornutum. In particular, the cyclin gene family was found to be expanded extensively compared to that of other eukaryotes and a novel type of cyclins was discovered, the diatom-specific cyclins. We established a synchronization method for P. tricornutum that enabled assignment of the different annotated genes to specific cell cycle phase transitions. The diatom-specific cyclins are predominantly expressed at the G1-to-S transition and some respond to phosphate availability, hinting at a role in connecting cell division to environmental stimuli. The discovery of highly conserved and new cell cycle regulators suggests the evolution of unique control mechanisms for diatom cell division, probably contributing to their ability to adapt and survive under highly fluctuating environmental conditions.Genome biology 02/2010; 11(2):R17. · 6.63 Impact Factor