scholarly journals Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63.

1988 ◽  
Vol 8 (3) ◽  
pp. 1027-1035 ◽  
Author(s):  
R A Dubin ◽  
M J Charron ◽  
S R Haut ◽  
R B Needleman ◽  
C A Michels
Keyword(s):  
Constitutive Expression ◽  
Positive Function ◽  
Gene Products ◽  
Wild Type ◽  
Transcript Accumulation ◽  
Saccharomyces Carlsbergensis ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
Mutational Activation ◽  
Type Strains

Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

Constitutive expression of the maltose fermentative enzymes in Saccharomyces carlsbergensis is dependent upon the mutational activation of a nonessential homolog of MAL63

1988 ◽  
Vol 8 (3) ◽  
pp. 1027-1035
Author(s):  
R A Dubin ◽  
M J Charron ◽  
S R Haut ◽  
R B Needleman ◽  
C A Michels
Keyword(s):  
Constitutive Expression ◽  
Positive Function ◽  
Gene Products ◽  
Wild Type ◽  
Transcript Accumulation ◽  
Saccharomyces Carlsbergensis ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
Mutational Activation ◽  
Type Strains

Maltose fermentation in Saccharomyces carlsbergensis is dependent upon the MAL6 locus. This complex locus is composed of the MAL61 and MAL62 genes, which encode maltose permease and maltase, respectively, and a third gene, MAL63, which codes for a trans-acting positive regulatory product. In wild-type strains, expression of the MAL61 and MAL62 mRNAs and proteins is induced by maltose and induction is dependent upon the MAL63 gene. Mutants constitutively expressing the MAL61 and MAL62 gene products have been isolated in mal63 backgrounds, and the mutations which have been analyzed map to a fourth MAL6-linked gene, MAL64. Cloning and characterization of this new gene are described in this report. The results revealed that the MAL64-C alleles present in constitutive strains encode a trans-acting positive function required for constitutive expression of the MAL61 and MAL62 gene products. In inducible strains, the MAL64 gene is dispensable, as deletion of the gene had no effect on maltose fermentation or maltose-regulated induction. MAL64 encoded transcripts of 2.0 and 1.4 kilobase pairs. While both MAL64 mRNAs were constitutively expressed in constitutive strains, they were maltose inducible in wild-type strains and induction was dependent upon the MAL63 gene. The MAL63 and MAL64 genes are at least partially structurally homologous, suggesting that they control MAL61 and MAL62 transcript accumulation by similar mechanisms.

Identification of a second trans-acting gene controlling maltose fermentation in Saccharomyces carlsbergensis

1986 ◽  
Vol 6 (8) ◽  
pp. 2757-2765
Author(s):  
R A Dubin ◽  
E L Perkins ◽  
R B Needleman ◽  
C A Michels
Keyword(s):  
Structural Gene ◽  
Regulatory Gene ◽  
Constitutive Expression ◽  
Gene Mutations ◽  
Gene Products ◽  
Structural Genes ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
New Gene

Maltose fermentation in Saccharomyces spp. requires the presence of a dominant MAL locus. The MAL6 locus has been cloned and shown to encode the structural genes for maltose permease (MAL61), maltase (MAL62), and a positively acting regulatory gene (MAL63). Induction of the MAL61 and MAL62 gene products requires the presence of maltose and the MAL63 gene. Mutations within the MAL63 gene produce nonfermenting strains unable to induce the two structural gene products. Reversion of these mal63 nonfermenters to maltose fermenters nearly always leads to the constitutive expression of maltase and maltose permease, and constitutivity is always linked to MAL6. We demonstrated that for one such revertant, strain C2, constitutivity did not require the MAL63 gene, since deletion disruption of this gene did not affect the constitutive expression of the structural genes. In addition, constitutivity was trans acting. Deletion disruption of the MAL6-linked structural genes for maltase and maltose permease in this strain did not affect the constitutive expression of a second, unlinked maltase structural gene. We isolated new maltose-fermenting revertants of a nonfermenting strain which carried a deletion disruption of the MAL63 gene. All 16 revertants isolated expressed maltase constitutively. In one revertant studied in detail, strain R10, constitutive expression was demonstrated to be linked to MAL6, semidominant, trans acting, and residing outside the MAL63-MAL61-MAL62 genes. From these studies we propose the existence of a second trans-acting regulatory gene at the MAL6 locus. We call this new gene MAL64. We mapped the MAL64 gene 2.3 centimorgans to the left of MAL63. The role of the MAL64 gene product in maltose fermentation is discussed.

scholarly journals Identification of a second trans-acting gene controlling maltose fermentation in Saccharomyces carlsbergensis.

1986 ◽  
Vol 6 (8) ◽  
pp. 2757-2765 ◽  
Author(s):  
R A Dubin ◽  
E L Perkins ◽  
R B Needleman ◽  
C A Michels
Keyword(s):  
Structural Gene ◽  
Regulatory Gene ◽  
Constitutive Expression ◽  
Gene Mutations ◽  
Gene Products ◽  
Structural Genes ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
New Gene

Maltose fermentation in Saccharomyces spp. requires the presence of a dominant MAL locus. The MAL6 locus has been cloned and shown to encode the structural genes for maltose permease (MAL61), maltase (MAL62), and a positively acting regulatory gene (MAL63). Induction of the MAL61 and MAL62 gene products requires the presence of maltose and the MAL63 gene. Mutations within the MAL63 gene produce nonfermenting strains unable to induce the two structural gene products. Reversion of these mal63 nonfermenters to maltose fermenters nearly always leads to the constitutive expression of maltase and maltose permease, and constitutivity is always linked to MAL6. We demonstrated that for one such revertant, strain C2, constitutivity did not require the MAL63 gene, since deletion disruption of this gene did not affect the constitutive expression of the structural genes. In addition, constitutivity was trans acting. Deletion disruption of the MAL6-linked structural genes for maltase and maltose permease in this strain did not affect the constitutive expression of a second, unlinked maltase structural gene. We isolated new maltose-fermenting revertants of a nonfermenting strain which carried a deletion disruption of the MAL63 gene. All 16 revertants isolated expressed maltase constitutively. In one revertant studied in detail, strain R10, constitutive expression was demonstrated to be linked to MAL6, semidominant, trans acting, and residing outside the MAL63-MAL61-MAL62 genes. From these studies we propose the existence of a second trans-acting regulatory gene at the MAL6 locus. We call this new gene MAL64. We mapped the MAL64 gene 2.3 centimorgans to the left of MAL63. The role of the MAL64 gene product in maltose fermentation is discussed.

Repeated Family of Genes Controlling Maltose Fermentation in Saccharomyces carlsbergensis

1983 ◽  
Vol 3 (5) ◽  
pp. 796-802
Author(s):  
Richard B. Needleman ◽  
Corinne Michels
Keyword(s):  
Genetic Analysis ◽  
Structural Gene ◽  
Regulatory Gene ◽  
Regulatory Protein ◽  
Physical Analysis ◽  
Saccharomyces Carlsbergensis ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
Complex Locus ◽  
Dna Fragment

Maltose fermentation in Saccharomyces spp. requires the presence of any one of five unlinked genes: MAL1, MAL2, MAL3, MAL4 , or MAL6. Although the genes are functionally equivalent, their natures and relationships to each other are not known. At least three proteins are necessary for maltose fermentation: maltase, maltose permease, and a regulatory protein. The MAL genes may code for one or more of these proteins. Recently a DNA fragment containing a maltase structural gene has been cloned from a MAL6 strain, CB11, to produce plasmid pMAL9-26. We have conducted genetic and physical analyses of strain CB11. The genetic analysis has demonstrated the presence of two cryptic MAL genes in CB11, MAL1g and MAL3g (linked to MAL1 and to MAL3 , respectively), in addition to the MAL6 locus. The physical analysis, which used a subclone of plasmid pMAL9-26 as a probe, detected three Hin dIII genomic fragments with homology to the probe. Each fragment was shown to be linked to one of the MAL loci genetically demonstrated to be present in CB11. Our results indicate that the cloned maltase structural gene in plasmid pMAL9-26 is linked to MAL6. Since the MAL6 locus has previously been shown to contain a regulatory gene, the MAL6 locus must be a complex locus containing at least two of the factors needed for maltose fermentation: the structural gene for maltase and the maltase regulatory protein. The absence of other fragments which hybridize to the MAL6 -derived probe shows that either MAL2 and MAL4 are not related to MAL6 , or the DNA corresponding to these genes is absent from the MAL6 strain CB11.

scholarly journals Mutants of Listeria monocytogenes Defective in In Vitro Invasion and Cell-to-Cell Spreading Still Invade and Proliferate in Hepatocytes of Neutropenic Mice

2000 ◽  
Vol 68 (2) ◽  
pp. 912-914 ◽  
Author(s):  
Rui Appelberg ◽  
Irene S. Leal
Keyword(s):  
Monoclonal Antibody ◽  
Listeria Monocytogenes ◽  
Cell Spreading ◽  
Histologic Examination ◽  
Gene Products ◽  
Wild Type ◽  
In Vitro Invasion ◽  
Parenchymal Cells ◽  
Type Strains

ABSTRACT Listeria monocytogenes mutants defective in theactA gene, the plcB gene, and theinlA and inlB genes were less virulent when injected intravenously into BALB/c mice. The growth of these strains as well as of the virulent wild-type strains was increased by treating mice with a neutrophil-specific depleting monoclonal antibody, RB6-8C5. Histologic examination of the livers of the treated animals showed intrahepatocytic proliferation of the listeriae in all cases. Our data show that more than one pathway exists that allows L. monocytogenes to invade parenchymal cells. One pathway most likely involves the actA and plcB gene products, and a second one probably involves the internalins.

scholarly journals Moraxella catarrhalis Strain O35E Expresses Two Filamentous Hemagglutinin-Like Proteins That Mediate Adherence to Human Epithelial Cells

2007 ◽  
Vol 75 (6) ◽  
pp. 2765-2775 ◽  
Author(s):  
Rachel Balder ◽  
Jonathan Hassel ◽  
Serena Lipski ◽  
Eric R. Lafontaine
Keyword(s):  
Epithelial Cells ◽  
Moraxella Catarrhalis ◽  
Gram Negative Bacteria ◽  
Gene Products ◽  
Wild Type ◽  
Recombinant Bacteria ◽  
Human Epithelial Cells ◽  
Bacterial Outer Membrane ◽  
Isogenic Mutants ◽  
Type Strains

ABSTRACT Two-partner secretion (TPS) systems are a family of proteins being rapidly identified and characterized in a growing number of gram-negative bacteria. TPS systems mediate the secretion of proteins, many involved in virulence traits such as hemolysis, adherence to epithelial cells, inhibition of bacterial growth, and immunomodulation of the host. A TPS system typically consists of a transporter located in the bacterial outer membrane (OM) which is responsible for the recognition and secretion of at least one large exoprotein. Two of the better-characterized TPS systems specify the Bordetella pertussis FHA and Haemophilus influenzae HMW1/HMW2 proteins. We identified three gene products of Moraxella catarrhalis strain O35E that resemble TPS proteins and designated them MhaC (transporter), MhaB1 (exoprotein), and MhaB2 (exoprotein). Western blot analysis using anti-MhaC, or antibodies reacting to both MhaB1 and MhaB2 (MhaB-reactive), revealed that these antigens are expressed in the OM of 63% of isolates tested. Mutations in the mhaC gene specifying the putative transporter of the M. catarrhalis wild-type strains O35E, O12E, and McGHS1 resulted in the absence of MhaB1/MhaB2 in the OM of mutants. These results are therefore consistent with the Mha proteins functioning as a TPS system. Furthermore, we discovered that these mhaC mutants exhibit markedly decreased binding to human epithelial cells relevant to pathogenesis by M. catarrhalis (Chang, HEp2, A549, and/or 16HBE14o−). Expression of O12E MhaC and MhaB1 in a nonadherent strain of Escherichia coli was found to increase the adherence of recombinant bacteria to HEp2 monolayers by sevenfold, thereby demonstrating that this M. catarrhalis TPS system directly mediates binding to human epithelial cells. The construction of isogenic mutants in the mhaB1 and mhaB2 genes of strain O35E also suggests that the MhaB proteins play distinct roles in M. catarrhalis adherence.

scholarly journals The characteristics of eleven mutants of R-factor R57 constitutive for tetracycline resistance, selected and tested inEscherichia coliK12

1975 ◽  
Vol 25 (3) ◽  
pp. 297-311 ◽  
Author(s):  
E. C. R. Reeve ◽  
J. M. Robertson
Keyword(s):  
Escherichia Coli ◽  
Constitutive Expression ◽  
Tetracycline Resistance ◽  
Gene Products ◽  
Wild Type ◽  
Repressor Gene ◽  
Negative Type ◽  
R Factor

SUMMARYEleven mutants of R-factor R57 have been isolated which show constitutive expression of resistance to tetracycline (Tc). These derepressed (Tdr) mutants all gave a much greater resistance to Tc and to its analogue, minocycline, than could be obtained by optimal induction of cells carrying the wild-type (T+) determinant. Cells carrying each of the Tdr mutants together with T+of either R6-S or of a plasmid found inEscherichia colimi19 showed inducible Tc resistance, indicating that the Tdr mutants were all recessive, i.e. of repressor-negative type. Tdr1 was not recessive to the T-determinant of RP1, suggesting that the repressor gene products of the T-determinants in R57 and RP1 have different specificities.

scholarly journals Moderate-Level Resistance to Glycopeptide LY333328 Mediated by Genes of the vanA and vanB Clusters in Enterococci

1999 ◽  
Vol 43 (8) ◽  
pp. 1875-1880 ◽  
Author(s):  
Michel Arthur ◽  
Florence Depardieu ◽  
Peter Reynolds ◽  
Patrice Courvalin
Keyword(s):  
Gene Cluster ◽  
Culture Medium ◽  
Constitutive Expression ◽  
Single Step ◽  
Moderate Level ◽  
Wild Type ◽  
Glycopeptide Resistance ◽  
Unknown Mechanism ◽  
Type Strains ◽  
Level Resistance

ABSTRACT Three of five natural plasmids carrying a wild-typevanA gene cluster did not confer LY333328 glycopeptide resistance on Enterococcus faecalis JH2-2 (MIC = 2 μg/ml). The two remaining plasmids conferred resistance to the drug (MIC, 8 μg/ml). The vanB gene cluster did not confer resistance to LY333328, since this antibiotic was not an inducer. Mutations in the vanSB sensor gene that allowed induction by teicoplanin or constitutive expression of thevanB cluster led to LY333328 resistance (MIC, 8 to 16 μg/ml). Overproduction of the VanH, VanA, and VanX proteins ford-alanyl-d-lactate (d-Ala-d-Lac) synthesis andd-Ala-d-Ala hydrolysis was sufficient for resistance to LY333328 (MIC, 16 μg/ml). Mutations in the hostd-Ala:d-Ala ligase contributed to LY333328 resistance in certain VanA- and VanB-type strains, but the MICs of the antibiotic did not exceed 16 μg/ml. Addition ofd-2-hydroxybutyrate in the culture medium of mutants that did not produce the VanH d-lactate dehydrogenase led to incorporation of this d-2-hydroxy acid at the C-terminal ends of the peptidoglycan precursors and to LY333328 resistance (MIC, 64 μg/ml). The vanZ gene of the vanA cluster conferred resistance to LY333328 (MIC, 8 μg/ml) by an unknown mechanism. These data indicate that VanA- and VanB-type enterococci may acquire moderate-level resistance to LY333328 (MIC ≤ 16 μg/ml) in a single step by various mechanisms.

The Constitutive, Glucose-Repression-Insensitive Mutation of the Yeast MAL4 Locus Is an Alteration of the MAL43 Gene

Genetics ◽  
1987 ◽  
Vol 116 (1) ◽  
pp. 23-31
Author(s):  
Maureen J Charron ◽  
Corinne A Michels
Keyword(s):  
Glucose Repression ◽  
Regulatory Gene ◽  
Constitutive Expression ◽  
Structural Genes ◽  
Wild Type ◽  
Gene Encoding ◽  
Maltose Permease ◽  
Genes Expression ◽  
Constitutive Production ◽  
Saccharomyces Yeasts

ABSTRACT Mutations resulting in constitutive production of maltase have been identified at each of the five MAL loci of Saccharomyces yeasts. Here we examine a dominant constitutive, glucose-repression-insensitive allele of the MAL4 locus (MAL4-C). Our results demonstrate that MAL4-C is an alteration in the MAL43 gene, which encodes the positive regulator of the MAL structural genes, and that its product is trans-acting. The MAL43 gene from the MAL4-C strain was cloned and integrated into a series of nonfermenting strains lacking a functional regulatory gene but carrying copies of the maltose permease and maltase structural genes. Expression of the maltase structural gene was both constitutive and insensitive to glucose repression in these transformants. The MAL4-C allele also results in constitutive expression of the unlinked MAL12 gene (encoding maltase) in this strain. In addition, the cloned MAL43 gene was shown to be dominant to the wild-type MAL63 gene. We also show that most of the glucose repression insensitivity of strains carrying the MAL4-C allele results from alteration of MAL43.

Identification of a baculovirus polyhedron formation mutant with a novel phenotype

1996 ◽  
Vol 54 ◽  
pp. 796-797
Author(s):  
James M. Slavicek ◽  
Melissa J. Mercer ◽  
Mary Ellen Kelly
Keyword(s):  
Viral Gene ◽  
Gene Products ◽  
Type Number ◽  
Infection Cycle ◽  
Wild Type ◽  
Protein Matrix ◽  
Insect Midgut ◽  
Viral Particles ◽  
Budded Virus ◽  
Viral Form

Nucleopolyhedroviruses (NPV, family Baculoviridae) produce two morphological forms, a budded virus form and a viral form that is occluded into a paracrystalline protein matrix. This structure is termed a polyhedron and is composed primarily of the protein polyhedrin. Insects are infected by NPVs after ingestion of the polyhedron and release of the occluded virions through dissolution of the polyhedron in the alkaline environment of the insect midgut. Early after infection the budded virus form is produced. It buds through the plasma membrane and then infects other cells. Later in the infection cycle the occluded form of the virus is generated (reviewed by Blissard and Rohrmann, 1990).The processes of polyhedron formation and virion occlusion are likely to involve a number of viral gene products. However, only two genes, the polyhedrin gene and 25K FP gene, have been identified to date that are necessary for the wild type number of polyhedra to be formed and viral particles occluded.

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