Evidence for cellular control in the synthesis of acetoin or α-ketoisovaleric acid by microorganisms

1974 ◽  
Vol 20 (6) ◽  
pp. 805-811 ◽  
Author(s):  
E. B. Collins ◽  
R. A. Speckman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Steady State ◽  
Serratia Marcescens ◽  
Lactobacillus Casei ◽  
Optically Active ◽  
Cell Free Extract ◽  
Data Support ◽  
A Cell ◽  
Cellular Control ◽  
Spent Media

Commercial α-acetolactate at pH 4.5 decarboxylated nonenzymatically (5 to 8%/h) to acetoin (69%) and diacetyl (31%), and an extract of Streptococcus diacetilactis 18-16 produced α-acetolactate (in addition to acetoin and diacetyl) from pyruvate in the presence of TPP and MgSO4. Nevertheless, α-acetolactate was not dispersed into media by any of four microorganisms (S. diacetilactis, strains 18-16 and DRC1, Saccharomyces cerevisiae 299, and Lactobacillus casei 393) that produced diacetyl and acetoin or by one (Serratia marcescens) that produced only acetoin. Lactobacillus casei and S. diacetilactis 18-16 produced unknown compounds that falsely indicated the presence of α-acetolactate when tests were made without separating acetoin and diacetyl from other components of the spent media. The production of acetoin by S. diacetilactis 18-16 was not inhibited by valine, the acetoin produced by this organism was optically active (+101.0°), and a cell-free extract of S. marcescens did not produce diacetyl while producing a large amount of acetoin. Data support the conclusion that the conversion of pyruvate to acetoin by some microorganisms and to α-ketoisovaleric acid by others is enzymatic and under cellular control, resulting in the synthesis of only steady-state amounts of enzymatically bound α-acetolactate in each of the pathways.

scholarly journals Hydrolysis of κ-casein in solution by chymosin, plasmin, trypsin and Lactobacillus -proteinases

1993 ◽  
Vol 2 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Anne Pihlanto-Leppälä ◽  
Eero Pahkala ◽  
Veijo Antila
Keyword(s):  
Proteolytic Activity ◽  
Lactobacillus Casei ◽  
Terminal Region ◽  
Lactobacillus Helveticus ◽  
Cell Free Extract ◽  
Enzyme Substrate ◽  
A Cell ◽  
Substrate Ratio ◽  
Almost All ◽  
Hydrolysis Of

The aim of this study was to examine the enzymatic hydrolysis of κ-casein by isolating and identifying the released peptides. The enzymes employed in the study were chymosin, plasmin and trypsin, as well as a cell-free extract from three Lactobacillus helveticus and nine Lactobacillus casei strains. The findings showed that the bond most sensitive to the proteolytic activity of chymosin was the Phe 105-Met 106. After 24 hours of hydrolysis a few other bonds in the casein macropeptide were also cleaved. Plasmin was found to have weak proteolytic activity under the conditions of this study. When the enzyme-substrate ratio was raised from 1:200 to 1:50, a few peptides were released from the N-terminal region. Trypsin was found to hydrolyze several κ-casein bonds, and peptides were released from almost all regions of the protein. The proteases of Lactobacillus had less effect than chymosin, plasmin or trypsin. The strains could be divided into three categories. L. helveticus strains had activity on bonds in the mid-section and C-terminal region, L. casei strains EB, P3, P8 and A 1 had activity on bonds in the N- and C-terminal regions, while L. casei A5 and M9 had activity only on bonds in the C-terminal region.

scholarly journals Underproduction of the Largest Subunit of RNA Polymerase II Causes Temperature Sensitivity, Slow Growth, and Inositol Auxotrophy in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 737-747 ◽  
Author(s):  
Jacques Archambault ◽  
David B Jansma ◽  
James D Friesen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Steady State ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Reporter Gene ◽  
Growth Medium ◽  
Temperature Sensitivity ◽  
Slow Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genes Encoding

Abstract In the yeast Saccharomyces cerevisiae, mutations in genes encoding subunits of RNA polymerase II (RNAPII) often give rise to a set of pleiotropic phenotypes that includes temperature sensitivity, slow growth and inositol auxotrophy. In this study, we show that these phenotypes can be brought about by a reduction in the intracellular concentration of RNAPII. Underproduction of RNAPII was achieved by expressing the gene (RPO21), encoding the largest subunit of the enzyme, from the LEU2 promoter or a weaker derivative of it, two promoters that can be repressed by the addition of leucine to the growth medium. We found that cells that underproduced RPO21 were unable to derepress fully the expression of a reporter gene under the control of the INO1 UAS. Our results indicate that temperature sensitivity, slow growth and inositol auxotrophy is a set of phenotypes that can be caused by lowering the steady-state amount of RNAPII; these results also lead to the prediction that some of the previously identified RNAPII mutations that confer this same set of phenotypes affect the assembly/stability of the enzyme. We propose a model to explain the hypersensitivity of INO1 transcription to mutations that affect components of the RNAPII transcriptional machinery.

scholarly journals Generation of catalytically active 6-phosphofructokinase from Saccharomyces cerevisiae in a cell-free system

2000 ◽  
Vol 267 (15) ◽  
pp. 4825-4830 ◽  
Author(s):  
Anke Edelmann ◽  
Jürgen Kirchberger ◽  
Manfred Naumann ◽  
Gerhard Kopperschläger
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Free System ◽  
Cell Free System ◽  
Catalytically Active ◽  
A Cell

Cellular Differentiation in Response to Nutrient Availability: The Repressor of Meiosis, Rme1p, Positively Regulates Invasive Growth in Saccharomyces cerevisiae

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1045-1058
Author(s):  
Dewald van Dyk ◽  
Guy Hansson ◽  
Isak S Pretorius ◽  
Florian F Bauer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cellular Differentiation ◽  
Promoter Sequence ◽  
Quiescent State ◽  
Invasive Growth ◽  
Limited Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
A Cell ◽  
Signaling Modules ◽  
Differentiation Pathways

Abstract In the yeast Saccharomyces cerevisiae, the transition from a nutrient-rich to a nutrient-limited growth medium typically leads to the implementation of a cellular adaptation program that results in invasive growth and/or the formation of pseudohyphae. Complete depletion of essential nutrients, on the other hand, leads either to entry into a nonbudding, metabolically quiescent state referred to as G0 in haploid strains or to meiosis and sporulation in diploids. Entry into meiosis is repressed by the transcriptional regulator Rme1p, a zinc-finger-containing DNA-binding protein. In this article, we show that Rme1p positively regulates invasive growth and starch metabolism in both haploid and diploid strains by directly modifying the transcription of the FLO11 (also known as MUC1) and STA2 genes, which encode a cell wall-associated protein essential for invasive growth and a starch-degrading glucoamylase, respectively. Genetic evidence suggests that Rme1p functions independently of identified signaling modules that regulate invasive growth and of other transcription factors that regulate FLO11 and that the activation of FLO11 is dependent on the presence of a promoter sequence that shows significant homology to identified Rme1p response elements (RREs). The data suggest that Rme1p functions as a central switch between different cellular differentiation pathways.

Codon replacement in the PGK1 gene of Saccharomyces cerevisiae: experimental approach to study the role of biased codon usage in gene expression

1987 ◽  
Vol 7 (8) ◽  
pp. 2914-2924
Author(s):  
A Hoekema ◽  
R A Kastelein ◽  
M Vasser ◽  
H A de Boer
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Steady State ◽  
Codon Usage ◽  
Experimental Approach ◽  
Mrna Translation ◽  
Yeast Cells ◽  
Expression Level ◽  
Start Codon ◽  
Mrna Levels

The coding sequences of genes in the yeast Saccharomyces cerevisiae show a preference for 25 of the 61 possible coding triplets. The degree of this biased codon usage in each gene is positively correlated to its expression level. Highly expressed genes use these 25 major codons almost exclusively. As an experimental approach to studying biased codon usage and its possible role in modulating gene expression, systematic codon replacements were carried out in the highly expressed PGK1 gene. The expression of phosphoglycerate kinase (PGK) was studied both on a high-copy-number plasmid and as a single copy gene integrated into the chromosome. Replacing an increasing number (up to 39% of all codons) of major codons with synonymous minor ones at the 5' end of the coding sequence caused a dramatic decline of the expression level. The PGK protein levels dropped 10-fold. The steady-state mRNA levels also declined, but to a lesser extent (threefold). Our data indicate that this reduction in mRNA levels was due to destabilization caused by impaired translation elongation at the minor codons. By preventing translation of the PGK mRNAs by the introduction of a stop codon 3' and adjacent to the start codon, the steady-state mRNA levels decreased dramatically. We conclude that efficient mRNA translation is required for maintaining mRNA stability in S. cerevisiae. These findings have important implications for the study of the expression of heterologous genes in yeast cells.

A heat-labile factor promotes premature 3' end formation in exon 1 of the murine adenosine deaminase gene in a cell-free transcription system

1991 ◽  
Vol 11 (11) ◽  
pp. 5398-5409
Author(s):  
J W Innis ◽  
R E Kellems
Keyword(s):  
Steady State ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Adenosine Deaminase ◽  
Free System ◽  
Cell Free System ◽  
Transcription System ◽  
Exon 1 ◽  
A Cell ◽  
Processed Products

An elongation block to RNA polymerase II transcription in exon 1 is a major regulatory step in expression of the murine adenosine deaminase (ADA) gene. Previous work in the laboratory identified abundant short transcripts with 3' termini in exon 1 in steady-state RNA from injected oocytes. Using a cell-free system to investigate the mechanism of premature 3' end formation, we found that polymerase II generates prominent ADA transcripts approximately 96 to 100 nucleotides in length which are similar to the major short transcripts found in steady-state RNA from oocytes injected with ADA templates. We have determined that these transcripts are the processed products of 108- to 112-nucleotide precursors. Precursor formation is (i) favored in reactions using circular templates, (ii) not the result of a posttranscriptional processing event, (iii) sensitive to low concentrations of Sarkosyl, and (iv) dependent on a factor(s) which is inactivated in crude extracts at 47 degrees C for 15 min. The cell-free system will allow further characterization of the template and factor requirements involved in the control of premature 3' end formation by RNA polymerase II.

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