Aspergillus nidulans Mutants Defective in stc Gene Cluster Regulation

Genetics ◽  
1999 ◽  
Vol 153 (2) ◽  
pp. 715-720 ◽  
Author(s):  
Robert A E Butchko ◽  
Thomas H Adams ◽  
Nancy P Keller
Keyword(s):  
Aspergillus Nidulans ◽  
Gene Cluster ◽  
Growth And Development ◽  
Biosynthetic Pathway ◽  
The Other ◽  
Wild Type ◽  
Norsolorinic Acid ◽  
Genetic Block ◽  
Colored Compound ◽  
Cluster Activity

Abstract The genes involved in the biosynthesis of sterigmatocystin (ST), a toxic secondary metabolite produced by Aspergillus nidulans and an aflatoxin (AF) precursor in other Aspergillus spp., are clustered on chromosome IV of A. nidulans. The sterigmatocystin gene cluster (stc gene cluster) is regulated by the pathway-specific transcription factor aflR. The function of aflR appears to be conserved between ST- and AF-producing aspergilli, as are most of the other genes in the cluster. We describe a novel screen for detecting mutants defective in stc gene cluster activity by use of a genetic block early in the ST biosynthetic pathway that results in the accumulation of the first stable intermediate, norsolorinic acid (NOR), an orange-colored compound visible with the unaided eye. We have mutagenized this NOR-accumulating strain and have isolated 176 Nor- mutants, 83 of which appear to be wild type in growth and development. Sixty of these 83 mutations are linked to the stc gene cluster and are likely defects in aflR or known stc biosynthetic genes. Of the 23 mutations not linked to the stc gene cluster, 3 prevent accumulation of NOR due to the loss of aflR expression.

scholarly journals A Screen for Genes That Function in Abscisic Acid Signaling in Arabidopsis thaliana

Genetics ◽  
2002 ◽  
Vol 161 (3) ◽  
pp. 1247-1255 ◽  
Author(s):  
Eiji Nambara ◽  
Masaharu Suzuki ◽  
Suzanne Abrams ◽  
Donald R McCarty ◽  
Yuji Kamiya ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Growth And Development ◽  
Plant Hormone ◽  
The Other ◽  
Aba Signaling ◽  
Wild Type ◽  
Plant Growth And Development ◽  
Diverse Range ◽  
Abscisic Acid Signaling ◽  
Aba Insensitive

Abstract The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development under a diverse range of environmental conditions. To identify genes functioning in ABA signaling, we have carried out a screen for mutants that takes advantage of the ability of wild-type Arabidopsis seeds to respond to (−)-(R)-ABA, an enantiomer of the natural (+)-(S)-ABA. The premise of the screen was to identify mutations that preferentially alter their germination response in the presence of one stereoisomer vs. the other. Twenty-six mutants were identified and genetic analysis on 23 lines defines two new loci, designated CHOTTO1 and CHOTTO2, and a collection of new mutant alleles of the ABA-insensitive genes, ABI3, ABI4, and ABI5. The abi5 alleles are less sensitive to (+)-ABA than to (−)-ABA. In contrast, the abi3 alleles exhibit a variety of differences in response to the ABA isomers. Genetic and molecular analysis of these alleles suggests that the ABI3 transcription factor may perceive multiple ABA signals.

scholarly journals Genome mining of novel rubiginones from Streptomyces sp. CB02414 and characterization of the post-PKS modification steps in rubiginone biosynthesis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Jingyan Zhang ◽  
Ying Sun ◽  
Yeji Wang ◽  
Xin Chen ◽  
Lu Xue ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Biosynthetic Pathway ◽  
Scale Up ◽  
Genome Mining ◽  
Gene Clusters ◽  
Combinatorial Biosynthesis ◽  
Wild Type ◽  
Aromatic Polyketides ◽  
A Genome

Abstract Background Rubiginones belong to the angucycline family of aromatic polyketides, and they have been shown to potentiate the vincristine (VCR)-induced cytotoxicity against VCR-resistant cancer cell lines. However, the biosynthetic gene clusters (BGCs) and biosynthetic pathways for rubiginones have not been reported yet. Results In this study, based on bioinformatics analysis of the genome of Streptomyces sp. CB02414, we predicted the functions of the two type II polyketide synthases (PKSs) BGCs. The rub gene cluster was predicted to encode metabolites of the angucycline family. Scale-up fermentation of the CB02414 wild-type strain led to the discovery of eight rubiginones, including five new ones (rubiginones J, K, L, M, and N). Rubiginone J was proposed to be the final product of the rub gene cluster, which features extensive oxidation on the A-ring of the angucycline skeleton. Based on the production profiles of the CB02414 wild-type and the mutant strains, we proposed a biosynthetic pathway for the rubiginones in CB02414. Conclusions A genome mining strategy enabled the efficient discovery of new rubiginones from Streptomyces sp. CB02414. Based on the isolated biosynthetic intermediates, a plausible biosynthetic pathway for the rubiginones was proposed. Our research lays the foundation for further studies on the mechanism of the cytochrome P450-catalyzed oxidation of angucyclines and for the generation of novel angucyclines using combinatorial biosynthesis strategies.

Developmentally related changes in the production and expression of endo-β-1,4-glucanases in Aspergillus nidulans

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 288-292 ◽  
Author(s):  
P. S. Bagga ◽  
S. Sharma ◽  
D. K. Sandhu
Keyword(s):  
Aspergillus Nidulans ◽  
The Other ◽  
Wild Type ◽  
Stages Of Development ◽  
Experimental Conditions ◽  
The Third ◽  
Developmental Mutants ◽  
Mutant Strains ◽  
In The Wild ◽  
Low Levels

The production and electrophoretic expression of endoglucanase(s) were compared in the wild-type and three developmental mutants of Aspergillus nidulans. In the wild type, the production of endoglucanase and its distribution in extracellular and intracellular fractions varied with the age of the culture and the yield was better in stable cultures (production of conidia and cleistothecia) as compared with shake cultures (vegetative hyphae only). Two developmental mutants, aco-T69 and aco-40, which lack the development of conidia and cleistothecia, produced low levels of endoglucanase enzymes as compared with the wild type grown under similar conditions. On the other hand, in aco-90, a mutant capable of producing cleistothecia but no conidia, endoglucanase production was better. The results indicate a correlation between cleistothecial development and endoglucanase level. The electrophoretic studies revealed the presence of three forms of endoglucanase, i.e., EGI, EGII, and EGIII. The first two were detectable in the wild type as well as in mutant strains when grown under various experimental conditions and at all the stages of development. However, the third form could be observed only during cleistothecial development, indicating that this isozyme is developmentally regulated.Key words: endoglucanases, development, Aspergillus nidulans.

scholarly journals Selective overexpression of the QUTE gene encoding catabolic 3-dehydroquinase in multicopy transformants of Aspergillus nidulans

1990 ◽  
Vol 265 (2) ◽  
pp. 337-342 ◽  
Author(s):  
R K Beri ◽  
S Grant ◽  
C F Roberts ◽  
M Smith ◽  
A R Hawkins
Keyword(s):  
Chlorogenic Acid ◽  
Aspergillus Nidulans ◽  
Gene Cluster ◽  
Quinic Acid ◽  
The Other ◽  
Gene Encoding ◽  
Repressor Gene ◽  
Catabolic Enzymes ◽  
Multiple Copies

The three enzymes necessary to catabolize quinate to protocatechuate are inducible by quinic acid, and transcription of their corresponding genes is controlled by the action of a positively acting activator gene and a negatively acting repressor gene. Transformed strains of Aspergillus nidulans containing multiple copies of the activator gene (QUTA) but single copies of the other QUT genes retain normal regulation of the gene cluster and do not show any overexpression of the three quinic acid catabolic enzymes. Transformed strains containing equal multiple copies of the activator gene (QUTA) and QUTE (encoding catabolic 3-dehydroquinase), but single copies of the other QUT genes, retain normal regulation of the QUT gene cluster, but selectively overexpress the QUTE gene upon quinic acid induction. Data are presented that strongly suggested that the gene QUTG, which is physically located within the QUT gene cluster and for which no function has been identified, is not required for expression of the gene cluster and does not encode a chlorogenic acid esterase.

Autogenous regulation of the positive regulatory qa-1F gene in Neurospora crassa

1985 ◽  
Vol 5 (12) ◽  
pp. 3593-3599
Author(s):  
V B Patel ◽  
N H Giles
Keyword(s):  
Neurospora Crassa ◽  
Gene Cluster ◽  
Dna Sequences ◽  
Regulatory Gene ◽  
Quinic Acid ◽  
The Other ◽  
Wild Type ◽  
Low Level ◽  
Activator Protein ◽  
Autogenous Regulation

In Neurospora crassa, the qa-1F regulatory gene positively controls transcription of all genes in the quinic acid (qa) gene cluster. qa-1F is transcribed at a low, uninduced level but is subject to strong (50-fold), autogenous regulation as well as to control by the negative regulatory gene, qa-1S, and the inducer quinic acid. Cloned qa-1F DNA sequences hybridize to two related mRNAs of 2.9 and 3.0 kilobases. When wild-type (qa-1F+) cultures are transferred to inducing conditions, qa-1F mRNA increases for 4 h, remains somewhat level, and decreases after 8 to 10 h. That this control is autogenous, i.e., that the qa-1F gene controls the synthesis of its own mRNA, is indicated by the presence of approximately the same low level of qa-1F mRNA in poly(A)+ RNA from noninducible qa-1F- mutant cultures under inducing conditions as that observed in uninduced wild-type cultures. The qa-1S gene also regulates the transcription of qa-1F, since a qa-1S- mutant, whether in noninducing or inducing conditions, contains a level of qa-1F mRNA that corresponds to the low level observed in uninduced wild-type cultures. These results corroborate the hypothesis (M. E. Case and N. H. Giles, Proc. Natl. Acad. Sci. USA 72:553-557, 1975; V. B. Patel, M. Schweizer, C. C. Dykstra, S. R. Kushner, and N. H. Giles, Proc. Natl. Acad. Sci. USA 78:5783-5787, 1981; L. Huiet, Proc. Natl. Acad. Sci. USA 81:1174-1178, 1984) that the qa-1F gene encodes an activator protein and acts positively in controlling transcription of itself and the other qa genes.

scholarly journals Autogenous regulation of the positive regulatory qa-1F gene in Neurospora crassa.

1985 ◽  
Vol 5 (12) ◽  
pp. 3593-3599 ◽  
Author(s):  
V B Patel ◽  
N H Giles
Keyword(s):  
Neurospora Crassa ◽  
Gene Cluster ◽  
Dna Sequences ◽  
Regulatory Gene ◽  
Quinic Acid ◽  
The Other ◽  
Wild Type ◽  
Low Level ◽  
Activator Protein ◽  
Autogenous Regulation

In Neurospora crassa, the qa-1F regulatory gene positively controls transcription of all genes in the quinic acid (qa) gene cluster. qa-1F is transcribed at a low, uninduced level but is subject to strong (50-fold), autogenous regulation as well as to control by the negative regulatory gene, qa-1S, and the inducer quinic acid. Cloned qa-1F DNA sequences hybridize to two related mRNAs of 2.9 and 3.0 kilobases. When wild-type (qa-1F+) cultures are transferred to inducing conditions, qa-1F mRNA increases for 4 h, remains somewhat level, and decreases after 8 to 10 h. That this control is autogenous, i.e., that the qa-1F gene controls the synthesis of its own mRNA, is indicated by the presence of approximately the same low level of qa-1F mRNA in poly(A)+ RNA from noninducible qa-1F- mutant cultures under inducing conditions as that observed in uninduced wild-type cultures. The qa-1S gene also regulates the transcription of qa-1F, since a qa-1S- mutant, whether in noninducing or inducing conditions, contains a level of qa-1F mRNA that corresponds to the low level observed in uninduced wild-type cultures. These results corroborate the hypothesis (M. E. Case and N. H. Giles, Proc. Natl. Acad. Sci. USA 72:553-557, 1975; V. B. Patel, M. Schweizer, C. C. Dykstra, S. R. Kushner, and N. H. Giles, Proc. Natl. Acad. Sci. USA 78:5783-5787, 1981; L. Huiet, Proc. Natl. Acad. Sci. USA 81:1174-1178, 1984) that the qa-1F gene encodes an activator protein and acts positively in controlling transcription of itself and the other qa genes.

scholarly journals CHPA, a Cysteine- and Histidine-Rich-Domain-Containing Protein, Contributes to Maintenance of the Diploid State in Aspergillus nidulans

2004 ◽  
Vol 3 (4) ◽  
pp. 984-991 ◽  
Author(s):  
Ari Sadanandom ◽  
Kim Findlay ◽  
John H. Doonan ◽  
Paul Schulze-Lefert ◽  
Ken Shirasu
Keyword(s):  
Genetic Diversity ◽  
Aspergillus Nidulans ◽  
Growth And Development ◽  
Genome Instability ◽  
Protein A ◽  
Vital Role ◽  
Life Cycles ◽  
The Other ◽  
Targeted Disruption ◽  
Rich Domain

ABSTRACT The alternation of eukaryotic life cycles between haploid and diploid phases is crucial for maintaining genetic diversity. In some organisms, the growth and development of haploid and diploid phases are nearly identical, and one might suppose that all genes required for one phase are likely to be critical for the other phase. Here, we show that targeted disruption of the chpA (cysteine- and histidine-rich-domain- [CHORD]-containing protein A) gene in haploid Aspergillus nidulans strains gives rise to chpA knockout haploids and heterozygous diploids but no chpA knockout diploids. A. nidulans chpA heterozygous diploids showed impaired conidiophore development and reduced conidiation. Deletion of chpA from diploid A. nidulans resulted in genome instability and reversion to a haploid state. Thus, our data suggest a vital role for chpA in maintenance of the diploid phase in A. nidulans. Furthermore, the human chpA homolog, Chp-1, was able to complement haploinsufficiency in A. nidulans chpA heterozygotes, suggesting that the function of CHORD-containing proteins is highly conserved in eukaryotes.

scholarly journals Characterization of the Aspergillus nidulans Monodictyphenone Gene Cluster

2010 ◽  
Vol 76 (7) ◽  
pp. 2067-2074 ◽  
Author(s):  
Yi-Ming Chiang ◽  
Edyta Szewczyk ◽  
Ashley D. Davidson ◽  
Ruth Entwistle ◽  
Nancy P. Keller ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Gene Cluster ◽  
Biosynthetic Pathway ◽  
Bioinformatic Analysis ◽  
Deletion Strain

ABSTRACT Deletion of cclA, a component of the COMPASS complex of Aspergillus nidulans, results in the production of monodictyphenone and emodin derivatives. Through a set of targeted deletions in a cclA deletion strain, we have identified the genes required for monodictyphenone and emodin analog biosynthesis. Identification of an intermediate, endocrocin, from an mdpHΔ strain suggests that mdpH might encode a decarboxylase. Furthermore, by replacing the promoter of mdpA (a putative aflJ homolog) and mdpE (a putative aflR homolog) with the inducible alcA promoter, we have confirmed that MdpA functions as a coactivator. We propose a biosynthetic pathway for monodictyphenone and emodin derivatives based on bioinformatic analysis and characterization of biosynthetic intermediates.

scholarly journals Enhancing the Production of the Fungal Pigment Aurofusarin in Fusarium graminearum

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 485 ◽  
Author(s):  
Klaus Westphal ◽  
Rasmus Wollenberg ◽  
Florian-Alexander Herbst ◽  
Jens Sørensen ◽  
Teis Sondergaard ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Genetic Engineering ◽  
Gene Cluster ◽  
Fusarium Graminearum ◽  
Biosynthetic Pathway ◽  
Regulatory Effect ◽  
Wild Type ◽  
Vast Number ◽  
Natural Sources ◽  
Increasing Demand

There is an increasing demand for products from natural sources, which includes a growing market for naturally-produced colorants. Filamentous fungi produce a vast number of chemically diverse pigments and are therefore explored as an easily accessible source. In this study we examine the positive regulatory effect of the transcription factor AurR1 on the aurofusarin gene cluster in Fusarium graminearum. Proteomic analyses showed that overexpression of AurR1 resulted in a significant increase of five of the eleven proteins belonging to the aurofusarin biosynthetic pathway. Further, the production of aurofusarin was increased more than threefold in the overexpression mutant compared to the wild type, reaching levels of 270 mg/L. In addition to biosynthesis of aurofusarin, several yet undescribed putative naphthoquinone/anthraquinone analogue compounds were observed in the overexpression mutant. Our results suggest that it is possible to enhance the aurofusarin production through genetic engineering.

scholarly journals Increased Adherence to Caco-2 Cells Caused by Disruption of the yhiE and yhiF Genes in Enterohemorrhagic Escherichia coli O157:H7

2003 ◽  
Vol 71 (5) ◽  
pp. 2598-2606 ◽  
Author(s):  
Ichiro Tatsuno ◽  
Keiji Nagano ◽  
Kazuki Taguchi ◽  
Li Rong ◽  
Hiroshi Mori ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Dna Sequences ◽  
Type Iii Secretion ◽  
Enterohemorrhagic Escherichia Coli ◽  
The Other ◽  
Wild Type ◽  
Amino Acid Homology ◽  
Type Iii ◽  
Antigen Gene

ABSTRACT Adherence of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelium is essential for initiation of infections, including diarrhea, and expression of the genes of the locus of enterocyte effacement (LEE) is thought to be crucial for adherence. To identify genes involved in modulating the adherent capacity, bacteria collected from an EHEC O157:H7 strain (O157Sakai) mutagenized by mini-Tn5Km2 were screened for their ability to increase the number of microcolonies (MC) on Caco-2 cells and eight mutants with increased adherence were isolated. Analysis of the mini-Tn5Km2-flanked DNA sequences indicated that one possessed the insertion within an O157 antigen gene cluster, another possessed the insertion within the yhiF gene, and the remaining six mutants had their insertions in the yhiE gene. yhiE and yhiF products share amino acid homology (23% identity) to each other and with members of the LuxR family, which are known as transcriptional regulatory proteins. The mutant having the insertion within the O157 antigen gene cluster did not express the O157 side chain (as determined by agglutination test and immunoblotting with polyclonal O157-specific antiserum), unlike the other seven mutants. Importantly, the other mutants showed enhanced type III secretion. Levels of the related mRNAs of genes of the LEE, but not that of ler mRNA, were also increased compared with those in the wild type. Indeed, when we introduced an in-frame deletion into the yhiE or yhiF gene in O157Sakai, the capacity of the resultant mutants to adhere to Caco-2 cells was greatly increased. When one of the yhiE insertion mutants was orally inoculated into ICR mice, the number of bacteria shed into feces by day 14 was greater than that for the wild type. These results suggest that yhiE and yhiF are involved in the adherence of O157Sakai to epithelial cells as negative regulators for the expression of the genes required for the type III secretion system.

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