RESUMEN
During embryonic cell cycles, B-cyclin-CDKs function as the core component of an autonomous oscillator. Current models for the cell-cycle oscillator in nonembryonic cells are slightly more complex, incorporating multiple G1, S phase, and mitotic cyclin-CDK complexes. However, periodic events persist in yeast cells lacking all S phase and mitotic B-cyclin genes, challenging the assertion that cyclin-CDK complexes are essential for oscillations. These and other results led to the proposal that a network of sequentially activated transcription factors functions as an underlying cell-cycle oscillator. Here we examine the individual contributions of a transcription factor network and cyclin-CDKs to the maintenance of cell-cycle oscillations. Our findings suggest that while cyclin-CDKs are not required for oscillations, they do contribute to oscillation robustness. A model emerges in which cyclin expression (thereby, CDK activity) is entrained to an autonomous transcriptional oscillator. CDKs then modulate oscillator function and serve as effectors of the oscillator.
Asunto(s)
Ciclo Celular/genética , Quinasas Ciclina-Dependientes/fisiología , Regulación Fúngica de la Expresión Génica , Factores de Transcripción/fisiología , Levaduras/citología , Proteína Quinasa CDC2/genética , Proteína Quinasa CDC2/metabolismo , Proteína Quinasa CDC2/fisiología , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Levaduras/enzimología , Levaduras/genéticaRESUMEN
A novel transcription factor, TcAP2, was isolated from Taxus cuspidata by yeast one-hybrid strategy. This factor interacts with jasmonate- and elicitor-responsive element. Analysis of the deduced TcAP2 amino acid sequence revealed that TcAP2 contained a conserved AP2/ethylene-responsive element binding protein domain that consisted of 268 amino acids in a potential nuclear localization sequence. The factor of TcAP2 had a high homology, in its AP2 domain, to other AP2 family members. Based on phylogenetic analysis, it was different from other five DRE-binding proteins in their evolutionary relationship. The transcription of TcAP2 gene in yew accumulated primarily in young organs, such as young stems. Quantitative real-time RT-PCR analysis indicated that TcAP2 gene was inducible to express by treatments with methyl jasmonate plus salicylic acid, high salinity, and cold. This gene showed no response to either abscisic acid or drought treatment.
Asunto(s)
Acetatos/farmacología , Ciclopentanos/farmacología , ADN Complementario/genética , ADN Complementario/aislamiento & purificación , Oxilipinas/farmacología , Taxus/genética , Factores de Transcripción/genética , Secuencia de Aminoácidos , Secuencia de Bases , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Datos de Secuencia Molecular , Especificidad de Órganos/efectos de los fármacos , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Unión Proteica/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Elementos de Respuesta/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de Proteína , Estrés Fisiológico/efectos de los fármacos , Estrés Fisiológico/genética , Fracciones Subcelulares/efectos de los fármacos , Fracciones Subcelulares/metabolismoRESUMEN
Jatropha curcas L. is a highly drought and salt tolerant plant species that is typically used as a traditional folk medicine and biofuel crop in many countries. Understanding the molecular mechanisms that underlie the response to various abiotic environmental stimuli, especially to drought and salt stresses, in J. curcas could be important to crop improvement efforts. In this study, we cloned and characterized the gene for a late embryogenesis abundant (LEA) protein from J. curcas that we designated JcLEA. Sequence analyses showed that the JcLEA protein belongs to group 5, a subgroup of the LEA protein family. In young seedlings, expression of JcLEA is significantly induced by abscisic acid (ABA), dehydration, and salt stress. Subcellular localization analysis shows that that JcLEA protein is distributed in both the nucleus and cytoplasm. Moreover, based on growth status and physiological indices, the overexpression of JcLEA in transgenic Arabidopsis plants conferred increased resistance to both drought and salt stresses compared to the WT. Our data suggests that the group 5 JcLEA protein contributes to drought and salt stress tolerance in plants. Thus, JcLEA is a potential candidate gene for plant genetic modification.