Transcriptional regulation of the protein kinase a subunits in Saccharomyces cerevisiae during fermentative growth
YEAST
Authors: Galello, Fiorella; Pautasso, Constanza; Reca, Sol; Canonero, Luciana; Portela, Paula; Moreno, Silvia; Rossi, Silvia
Abstract
Yeast cells can adapt their growth in response to the nutritional environment. Glucose is the favourite carbon source of Saccharomyces cerevisiae, which prefers a fermentative metabolism despite the presence of oxygen. When glucose is consumed, the cell switches to the aerobic metabolism of ethanol, during the so-called diauxic shift. The difference between fermentative and aerobic growth is in part mediated by a regulatory mechanism called glucose repression. During glucose derepression a profound gene transcriptional reprogramming occurs and genes involved in the utilization of alternative carbon sources are expressed. Protein kinase A (PKA) controls different physiological responses following the increment of cAMP as a consequence of a particular stimulus. cAMP-PKA is one of the major pathways involved in the transduction of glucose signalling. In this work the regulation of the promoters of the PKA subunits during respiratory and fermentative metabolism are studied. It is demonstrated that all these promoters are upregulated in the presence of glycerol as carbon source through the Snf1/Cat8 pathway. However, in the presence of glucose as carbon source, the regulation of each PKA promoter subunits is different and only TPK1 is repressed by the complex Hxk2/Mig1 in the presence of active Snf1. Copyright (c) 2017 John Wiley & Sons, Ltd.
Molecular cloning of human thiamin pyrophosphokinase
BIOCHIMICA ET BIOPHYSICA ACTA-GENE STRUCTURE AND EXPRESSION
Authors: Zhao, RB; Gao, F; Goldman, ID
Abstract
Thiamin pyrophosphokinase (TPK, EC 2.7.6.2) catalyses phosphorylation of thiamin to thiamin pyrophosphate, an active enzyme cofactor. Here we describe the cloning of complete human TPK1 cDNA from an adult liver library. Human TPK1 is 89% identical to murine TPK1 at the protein level. The gene maps to chromosome 7q34-36, consists of at least eight exons, and spans a distance at least of 420 kb. The mRNA of human TPK1 is highly expressed in testis, small intestine and kidney with lesser but detectable expression in brain, liver, placenta and spleen. The availability of the human TPK1 gene will provide another useful tool for studying the role of this enzyme in human thiamin metabolism and deficiency state. (C) 2001 Elsevier Science B.V. All rights reserved.