Analysis of the site of action of the amdR product for regulation of the amdS gene of Aspergillus nidulans

1992 ◽  
Vol 235 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Tim G. Littlejohn ◽  
Michael J. Hynes
Keyword(s):  
Aspergillus Nidulans ◽  
Site Of Action ◽  
Amds Gene

Yeast proteins can activate expression through regulatory sequences of the amdS gene of Aspergillus nidulans

1995 ◽  
Vol 246 (2) ◽  
pp. 223-227 ◽  
Author(s):  
Nathalie Bonnefoy ◽  
Jane Copsey ◽  
Michael J. Hynes ◽  
Mervl A. Davis
Keyword(s):  
Aspergillus Nidulans ◽  
Regulatory Sequences ◽  
Amds Gene

scholarly journals How does the cell count the number of ectopic copies of a gene in the premeiotic inactivation process acting in Ascobolus immersus?

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 585-591 ◽  
Author(s):  
G Faugeron ◽  
L Rhounim ◽  
J L Rossignol
Keyword(s):  
Cell Count ◽  
Aspergillus Nidulans ◽  
Repeated Sequences ◽  
Duplicated Genes ◽  
Recombinant Strains ◽  
Integrative Transformation ◽  
Ascobolus Immersus ◽  
Multiple Copies ◽  
Amds Gene ◽  
Inactivation Process

Abstract Repeated genes, artificially introduced in Ascobolus immersus by integrative transformation, are frequently inactivated during the sexual phase. Inactivation is observed in about 50% of meioses if duplicated genes are at ectopic chromosomal locations, and in 90% of meioses if genes are tandemly repeated. Inactivation is associated with extensive methylation of the cytosine residues of the duplicated sequences and is induced in the still haploid nuclei of the dikaryotic cell which will undergo karyogamy and subsequent meiosis. Only repeated sequences become methylated. This raises the intriguing question of how the premeiotic inactivation machinery is informed that a nucleus contains multiple copies of a gene. By using in crosses recombinant strains of A. immersus in which either one, two or three genetically independent copies of the exogenous amdS gene from Aspergillus nidulans had been introduced, we could follow the premeiotic inactivation of each one of the ectopic amdS copies. This led us to propose that a prerequisite for inactivation is a premeiotic pairing of repeated sequences and that each copy can undergo successive cycles of pairing. In fact, once methylated, a copy can pair with a still unmethylated copy, so that an uneven number of copies can be subject to inactivation.

Identification of the sites of action for regulatory genes controlling the amdS gene of Aspergillus nidulans

1988 ◽  
Vol 8 (6) ◽  
pp. 2589-2596
Author(s):  
M J Hynes ◽  
C M Corrick ◽  
J M Kelly ◽  
T G Littlejohn
Keyword(s):  
Aspergillus Nidulans ◽  
Gene Product ◽  
Regulatory Gene ◽  
Gene Activation ◽  
Base Change ◽  
Product Introduction ◽  
Base Pairs ◽  
Cis Acting ◽  
Amds Gene ◽  
Sites Of Action

The amdS gene of Aspergillus nidulans, which encodes an acetamidase enzyme, is positively regulated by the trans-acting genes amdR, facB, amdA, and areA. Sequence changes in several cis-acting mutations in the 5' region of the gene which specifically affect amdS regulation were determined. The amdI9 mutation, which results in increased facB-dependent acetate induction, is due to a single-base change at base pair -210 relative to the start point of translation. The amdI93 mutation, which abolishes amdR-dependent omega-amino acid induction, is a deletion of base pairs -181 to -151. The amdI66 mutation, which causes increased gene activation in strains carrying amdA regulatory gene mutations, is a duplication of base pairs -107 to -90. Transformation of A. nidulans can generate transformants containing multiple integrated copies of plasmid sequences. When these plasmids carry a potential binding site for a regulatory gene product, growth on substrates whose catabolism requires genes activated by that regulatory gene can be reduced, apparently because of titration of the regulatory gene product. Introduction of 5' amdS sequences via cotransformation into strains of various genotypes was used to localize sequences apparently involved in binding of the products of the amdR, amdA, and facB genes. The position of these sequences is in agreement with the positions of the specific cis-acting mutations. Consistent with these results, a transformant of A. nidulans derived from a plasmid deleted for sequences upstream from -111 was found to have lost amdR- and facB-mediated control but was still regulated by the amdA gene. In addition, amdS expression in this transformant was still dependent on the areA gene.

Isolation of genomic clones containing the amdS gene of Aspergillus nidulans and their use in the analysis of structural and regulatory mutations

1983 ◽  
Vol 3 (8) ◽  
pp. 1430-1439 ◽  
Author(s):  
M J Hynes ◽  
C M Corrick ◽  
J A King
Keyword(s):  
Aspergillus Nidulans ◽  
Large Scale ◽  
Small Scale ◽  
Cis Acting ◽  
Physical Maps ◽  
Regulatory Circuits ◽  
Regulatory Mutations ◽  
Amds Gene ◽  
Chromosome Iii ◽  
High Level

Previous analysis of the amdS gene of Aspergillus nidulans has identified multiple regulatory circuits mediated by trans-acting regulatory genes, cis-acting mutations have been identified and shown to specifically affect individual regulatory circuits. Fine-structure genetic mapping of the amdS regions showed that these cis-acting mutations occur in a complex controlling region adjacent to the amdS structural gene. The amdS gene was cloned by differential hybridization, using cDNA probes derived from a high-level-producing strain and from a strain with a large amdS deletion mutation. RNA blotting experiments showed that a single RNA species of 1,600 to 1,700 base pairs is transcribed from the amdS gene. DNA blotting experiments on a large number of amdS mutant strains, including deletions and translocations, allowed the genetic and physical maps of the gene to be correlated. The controlling region of the gene is situated at the 5' end of the gene and the direction of transcription is toward the centromere of chromosome III. The regulatory mutations in the controlling region were found to be due to small-scale alterations in the DNA rather than to large-scale rearrangements resulting in gene fusions.

Isolation and analysis of the acetate regulatory gene, facB, from Aspergillus nidulans

1989 ◽  
Vol 9 (12) ◽  
pp. 5696-5701
Author(s):  
M E Katz ◽  
M J Hynes
Keyword(s):  
Aspergillus Nidulans ◽  
Regulatory Gene ◽  
Cosmid Library ◽  
Acetate Metabolism ◽  
Loss Of Function ◽  
Mutant Strains ◽  
Multiple Copies ◽  
Acetate Utilization ◽  
Amds Gene ◽  
Induction Of Enzymes

The facB gene of Aspergillus nidulans is thought to be involved in acetate induction of enzymes required for acetate utilization and of the acetamidase encoded by the multiply regulated amdS gene. In addition, some evidence suggests that the facB gene has a structural as well as a regulatory role in acetate metabolism. The facB gene was cloned from a cosmid library by complementation of the facB101 loss-of-function mutation. Transformants receiving multiple copies of facB displayed stronger growth on acetamide media, indicating increased amdS expression, while growth on acetate was inhibited in these multicopy transformants. A 3.1-kilobase acetate-inducible facB transcript was detected by Northern (RNA) blot analysis. Examination of message levels in wild-type and mutant strains indicated that the facB gene is subject to carbon catabolite repression. Previous work has indicated that the presence of multiple copies of the 5' end of the amdS gene can result in titration of regulatory proteins. Additional copies of the facB gene were shown to specifically overcome the effect of facB product titration.

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