Transcriptional responses to glucose in Saccharomyces cerevisiae strains lacking a functional protein kinase A

Background The pattern of gene transcripts in the yeast Saccharomyces cerevisiae is strongly affected by the presence of glucose. An increased activity of protein kinase A (PKA), triggered by a rise in the intracellular concentration of cAMP, can account for many of the effects of glucose on transcription. In S. cerevisiae three genes, TPK1, TPK2, and TPK3, encode catalytic subunits of PKA. The lack of viability of tpk1 tpk2 tpk3 triple mutants may be suppressed by mutations such as yak1 or msn2/msn4. To investigate the requirement for PKA in glucose control of gene expression, we have compared the effects of glucose on global transcription in a wild-type strain and in two strains devoid of PKA activity, tpk1 tpk2 tpk3 yak1 and tpk1 tpk2 tpk3 msn2 msn4. Results We have identified different classes of genes that can be induced -or repressed- by glucose in the absence of PKA. Representative examples are genes required for glucose utilization and genes involved in the metabolism of other carbon sources, respectively. Among the genes responding to glucose in strains devoid of PKA some are also controlled by a redundant signalling pathway involving PKA activation, while others are not affected when PKA is activated through an increase in cAMP concentration. On the other hand, among genes that do not respond to glucose in the absence of PKA, some give a full response to increased cAMP levels, even in the absence of glucose, while others appear to require the cooperation of different signalling pathways. We show also that, for a number of genes controlled by glucose through a PKA-dependent pathway, the changes in mRNA levels are transient. We found that, in cells grown in gluconeogenic conditions, expression of a small number of genes, mainly connected with the response to stress, is reduced in the strains lacking PKA. Conclusions In S. cerevisiae, the transcriptional responses to glucose are triggered by a variety of pathways, alone or in combination, in which PKA is often involved. Redundant signalling pathways confer a greater robustness to the response to glucose, while cooperative pathways provide a greater flexibility.BT/BiotechnologyApplied Science

Proteína kinasas dependientes de cAMP y señalización por glucosa en Saccharomyces cerevisiae

Tesis doctoral inédita realizada en la Universidad Autónoma de Madrid. Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 16 de Noviembre de 2010

Las protein kinasas dependientes de cAMP están implicadas en la inducción de invertasa por glucosa baja en Saccharomyces cerevisiae pero no en la represión por alta glucosa

Trabajo presentado en el XXXII Congreso Sociedad Española de Bioquímica y Biología Molecular, celebrado en Oviedo (España) del 23 al 26 de septiembre de 2009

cAMP-dependent protein kinases are involved in the induction of invertase by glucose in Saccharomyces cerevisiae

Trabajo presentado en el 27th Issy: Pasteur’s legacy – Yeasts for Health and Biotechnologies, celebrado en París (Francia) del 26 al 29 de agosto de 2009

About a heat and mass transfer process reflection in phase plane

Darbā aplūkota pirmās kārtas nelineāra parasto diferenciālvienādojumu sistēma, kura radusies apskatot koksnes žāvēšanas matemātisko modeli. Šī sistēma pārnesta fāzu plaknē, noskaidrota atrisinājuma atkarība no mitras koksnes blīvuma, apkārtējā gaisa plūsmas ātrumaun koka plāksnes biezuma vērtībām. Bibliogrāfijā 8 nosaukumi Atslēgas vārdi: pirmās kārtas nelineāra parasto diferenciālvienādojumu sistēma, fāzu plaknes analīzes metode.In this work was a system of first order nonlinear ordinary differential equation examined, that came from inspecting the model of wood drying. This system was transmitted in to phase plane and established the solutions dependence of wet web density, velocity of around air and wood plate thickness values. Bibliography 8 items Keywords: first order nonlinear ordinary differential equation system, phase plane analyses method