Effect of digitonin on membrane-bound and chitosomal chitin synthetase activity in protoplasts from yeast cells ofCandida albicans

1993 ◽  
Vol 64 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Daniel Gozalbo ◽  
Francisco Dub�n ◽  
Rafael Sentandreu
Keyword(s):  
Yeast Cells ◽  
Synthetase Activity ◽  
Chitin Synthetase ◽  
Ofcandida Albicans ◽  
Membrane Bound

scholarly journals Glucose Signaling Pathway and Growth Conditions Regulate Gene Expression in Retrotransposon Ty2

2009 ◽  
Vol 64 (7-8) ◽  
pp. 526-532 ◽  
Author(s):  
Sezai Türkel ◽  
Özgür Bayram ◽  
Elif Arık
Keyword(s):  
Gene Expression ◽  
Growth Conditions ◽  
Glucose Sensors ◽  
Yeast Cells ◽  
Growth Stages ◽  
Regulate Gene Expression ◽  
Glucose Signaling ◽  
Yeast Cultures ◽  
Membrane Bound ◽  
High Level

Gene expression in the yeast retrotransposon Ty2 is regulated at transcriptional and translational levels. In this study, we have shown that the transcription of Ty2 is partially dependent on the membrane-bound glucose sensors Gpr1p and Mth1p in Saccharomyces cerevisiae. Transcription of Ty2 decreased approx. 3-fold in the gpr1, mth1 yeast mutant. Moreover, our results revealed that the transcription of Ty2 fluctuates during the growth stages of S. cerevisae. Both transcription and the frameshift rate of Ty2 rapidly dropped when the stationary stage yeast cells were inoculated into fresh medium. There was an instant activation of Ty2 transcription and a high level expression during the entire logarithmic stage of yeast growth. However, the transcription of Ty2 decreased 2-fold when the yeast cultures entered the stationary stage. The frameshift rate in Ty2 also varied depending on the growth conditions. The highest frameshift level was observed during the mid-logarithmic stage. It decreased up to 2-fold during the stationary stage. Furthermore, we have found that the frameshift rate of Ty2 diminished at least 5-fold in slowly growing yeasts. These results indicate that the transcription and the frameshift efficiency are coordinately regulated in the retrotransposon Ty2 depending on the growth conditions of S. cerevisiae.

A Study on the Effect of Lysolecithin and Phospholipase A on Membrane-Bound Galactosyltransferase

1974 ◽  
Vol 52 (11) ◽  
pp. 1053-1066 ◽  
Author(s):  
Sailen Mookerjea ◽  
James W. M. Yung
Keyword(s):  
Liver Microsomes ◽  
Fatty Acyl ◽  
Phospholipase A ◽  
Synthetase Activity ◽  
Rat Liver Microsomes ◽  
Physiological Concentration ◽  
Activation Effect ◽  
Membrane Bound ◽  
Hydrolysis Of

Addition of lysolecithin caused very marked activation of UDP-galactose:glycoprotein galactosyltransferase in rat liver microsomes and in Golgi-rich membranes. Lysolecithin activated galactosyltransferase when the enzyme was assayed both with endogenous acceptor and with exogenous proteins or monosaccharides as acceptors. Lactose synthetase activity in presence of α-lactalbumin was also stimulated by lysolecithin. Lecithin, lysophosphatidylethanolamine, lysophosphatidic acid, and glycerophosphorylcholine did not activate the enzyme, suggesting that both fatty acyl and phosphorylcholine groups of the lysolecithin molecule are required for the observed activation. The degree of activation was about the same when myristoyl-, palmitoyl-, oleoyl-, or stearoyllysolecithin were tested. The activation by lysolecithin was observed well within the physiological concentration of the lipid in the liver cell. Saturating amounts of Triton masked the effect of lysolecithin.Brief preincubation with phospholipase A activated the enzyme and generated lysolecithin in the membranes. Triton and lysolecithin activated the enzyme without any lag time, whereas phospholipase A activation was dependent on preincubation and also on an alkaline pH favorable for the hydrolysis of phospholipid. EDTA blocked the activation effect of phospholipase A but had no effect on activation by lysolecithin. Albumin and cholesterol opposed the effects of lysolecithin and phospholipase A on the enzyme. Two successive incubations of the microsomes with lysolecithin caused considerable release of the enzyme into the soluble fraction. The role of lysolecithin in the activation of the enzyme is probably related to the solubilization of the membrane and consequent enhanced interaction of the enzyme with substrate. Lysolecithin also activated N-acetylglucosaminyl- and sialyltransferase activities in microsomes. A possible role of lysolecithin is indicated in the regulation of glycosylation reactions in mammalian system.

Chitin synthetase activity in a developmental mutant of Phycomyces blakesleeanus

1990 ◽  
Vol 58 (2) ◽  
pp. 67-72 ◽  
Author(s):  
E. Ruiz-Flores ◽  
E. Lopez-Romero ◽  
F. Gutierrez-Corona
Keyword(s):  
Synthetase Activity ◽  
Phycomyces Blakesleeanus ◽  
Chitin Synthetase ◽  
Developmental Mutant

Altered expression of chitin synthetase activity and biochemical changes in the cell wall in a developmental mutant ofPhycomyces

1988 ◽  
Vol 26 (11-12) ◽  
pp. 717-732 ◽  
Author(s):  
Elvia Ruiz-Flores ◽  
Everardo Lopez-Romero ◽  
Arturo Flores-Carreon ◽  
Felix Gutierrez-Corona
Keyword(s):  
Cell Wall ◽  
Biochemical Changes ◽  
Synthetase Activity ◽  
Altered Expression ◽  
Chitin Synthetase ◽  
Developmental Mutant

scholarly journals Quantitative characterisation of low abundant yeast mitochondrial proteins reveals compensation for haplo-insufficiency in different environments

2021 ◽  
Author(s):  
Alkisti Manousaki ◽  
James Bagnall ◽  
David Spiller ◽  
Michael White ◽  
Daniela Delneri
Keyword(s):  
Bound State ◽  
Correlation Spectroscopy ◽  
Yeast Cells ◽  
Compensatory Mechanism ◽  
Protein Abundance ◽  
Fluorescence Correlation ◽  
Non Invasive ◽  
Quantitative Characterisation ◽  
Membrane Bound ◽  
The Impact

Quantification of low abundant membrane-bound proteins such as transcriptional factors and chaperones has been proved difficult even with the most sophisticated analytical technologies. Here we exploit and optimise the non-invasive Fluorescence Correlation Spectroscopy (FCS) for quantitation of low abundance protein and as proof of principle we choose two interacting membrane-bound proteins involved in fission of mitochondria in yeast. In Saccharomyces cerevisiae the recruitment of Fis1p and Mdv1p fission proteins to mitochondria is essential for the scission of the organelles and the retention of functional mitochondrial structures in the cell. We used FCS in single, GFP-labelled live yeast cells to quantify the protein abundance in homozygote and heterozygote cells, and to investigate the impact of the environments on protein copy number, bound/unbound protein state and mobility kinetics. Both proteins were observed to localise predominantly at mitochondrial structures with the Mdv1p bound state increasing significantly in a strictly respiratory environment. Moreover, a compensatory mechanism which controls Fis1p abundance upon deletion of one allele was observed in Fis1p but not in Mdv1p, suggesting differential regulation of Fis1p and Mdv1p protein expression.

scholarly journals A Conserved Histidine Is Essential for Glycerolipid Acyltransferase Catalysis

1998 ◽  
Vol 180 (6) ◽  
pp. 1425-1430 ◽  
Author(s):  
Richard J. Heath ◽  
Charles O. Rock
Keyword(s):  
Aspartic Acid ◽  
Acyl Carrier Protein ◽  
Site Directed Mutagenesis ◽  
Carrier Protein ◽  
Synthetase Activity ◽  
Acyltransferase Activity ◽  
Acyl Acceptor ◽  
Aspartic Acid Residue ◽  
Membrane Bound

ABSTRACT Sequence analysis of membrane-bound glycerolipid acyltransferases revealed that proteins from the bacterial, plant, and animal kingdoms share a highly conserved domain containing invariant histidine and aspartic acid residues separated by four less conserved residues in an HX4D configuration. We investigated the role of the invariant histidine residue in acyltransferase catalysis by site-directed mutagenesis of two representative members of this family, the sn-glycerol-3-phosphate acyltransferase (PlsB) and the bifunctional 2-acyl-glycerophosphoethanolamine acyltransferase/acyl-acyl carrier protein synthetase (Aas) ofEscherichia coli. Both the PlsB[H306A] and Aas[H36A] mutants lacked acyltransferase activity. However, the Aas[H36A] mutant retained significant acyl-acyl carrier protein synthetase activity, illustrating that the lack of acyltransferase activity was specifically associated with the H36A substitution. The invariant aspartic acid residue in the HX4D pattern was also important. The substitution of aspartic acid 311 with glutamic acid in PlsB resulted in an enzyme with significantly reduced catalytic activity. Substitution of an alanine at this position eliminated acyltransferase activity; however, the PlsB[D311A] mutant protein did not assemble into the membrane, indicating that aspartic acid 311 is also important for the proper folding and membrane insertion of the acyltransferases. These data are consistent with a mechanism for glycerolipid acyltransferase catalysis where the invariant histidine functions as a general base to deprotonate the hydroxyl moiety of the acyl acceptor.

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