Binding of the C6-zinc cluster protein, AFLR, to the promoters of aflatoxin pathway biosynthesis genes in Aspergillus parasiticus

Ehrlich, Kenneth C.; Montalbano, Beverly G.; Cary, Jeffrey W.

doi:10.1016/s0378-1119(99)00075-x

Cited by 154 publications

(104 citation statements)

References 24 publications

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“…The aflR gene is the principal regulator of the aflatoxin production pathway (Chang et al, 1993;Payne et al, 1993;Woloshuk et al, 1994). Previous research has demonstrated that the AFLR protein can bind the promoter region of each aflatoxin synthesis gene and activate gene expression (Woloshuk et al, 1994;Trail et al, 1995;Ehrlich et al, 1999b). In addition, the aflR gene has an autoregulation function (Chang et al, 1995b).…”

Section: Resultsmentioning

confidence: 99%

“…Variability of promoter and zinc-finger motif of aflR et al (1995a) and Ehrlich et al (1999b) have studied aflR sequences in the region 2130 to 291, which may be important for aflR function, and have found that they are all the same, except at position 2115, where A. parasiticus/ A. sojae and A. flavus/A. oryzae have C and T, respectively (Table 3).…”

Section: Level Of Aflr Sequence Similaritymentioning

confidence: 99%

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Comparison of the aflR gene sequences of strains in Aspergillus section Flavi

2006

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Aflatoxins are polyketide-derived secondary metabolites produced by Aspergillus parasiticus, Aspergillus flavus, Aspergillus nomius and a few other species. The toxic effects of aflatoxins have adverse consequences for human health and agricultural economics. The aflR gene, a regulatory gene for aflatoxin biosynthesis, encodes a protein containing a zinc-finger DNA-binding motif. Although Aspergillus oryzae and Aspergillus sojae, which are used in fermented foods and in ingredient manufacture, have no record of producing aflatoxin, they have been shown to possess an aflR gene. This study examined 34 strains of Aspergillus section Flavi. The aflR gene of 23 of these strains was successfully amplified and sequenced. No aflR PCR products were found in five A. sojae strains or six strains of A. oryzae. These PCR results suggested that the aflR gene is absent or significantly different in some A. sojae and A. oryzae strains. The sequenced aflR genes from the 23 positive strains had greater than 96·6 % similarity, which was particularly conserved in the zinc-finger DNA-binding domain. The aflR gene of A. sojae has two obvious characteristics: an extra CTCATG sequence fragment and a C to T transition that causes premature termination of AFLR protein synthesis. Differences between A. parasiticus/A. sojae and A. flavus/A. oryzae aflR genes were also identified. Some strains of A. flavus as well as A. flavus var. viridis, A. oryzae var. viridis and A. oryzae var. effuses have an A. oryzae-type aflR gene. For all strains with the A. oryzae-type aflR gene, there was no evidence of aflatoxin production. It is suggested that for safety reasons, the aflR gene could be examined to assess possible aflatoxin production by Aspergillus section Flavi strains.

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Section: Resultsmentioning

confidence: 99%

Section: Level Of Aflr Sequence Similaritymentioning

confidence: 99%

Comparison of the aflR gene sequences of strains in Aspergillus section Flavi

2006

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“…Genes encoding enzymes of this pathway are located in a 70-kb gene cluster in both the Aspergillus flavus and Aspergillus parasiticus genomes (292). AflR positively regulates the expression of these genes by binding to the consensus motif TCGSWNNSCGR found in the promoters of target genes (58). Colletotrichum lagenarium is a plant pathogen that causes anthracnose of cucumbers.…”

Section: Zinc Cluster Proteins In Other Speciesmentioning

confidence: 99%

A Fungal Family of Transcriptional Regulators: the Zinc Cluster Proteins

MacPherson¹,

Larochelle²,

Turcotte

2006

Microbiol Mol Biol Rev

504

554

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SUMMARY The trace element zinc is required for proper functioning of a large number of proteins, including various enzymes. However, most zinc-containing proteins are transcription factors capable of binding DNA and are named zinc finger proteins. They form one of the largest families of transcriptional regulators and are categorized into various classes according to zinc-binding motifs. This review focuses on one class of zinc finger proteins called zinc cluster (or binuclear) proteins. Members of this family are exclusively fungal and possess the well-conserved motif CysX2CysX6CysX5-12CysX2CysX6-8Cys. The cysteine residues bind to two zinc atoms, which coordinate folding of the domain involved in DNA recognition. The first- and best-studied zinc cluster protein is Gal4p, a transcriptional activator of genes involved in the catabolism of galactose in the budding yeast Saccharomyces cerevisiae. Since the discovery of Gal4p, many other zinc cluster proteins have been characterized; they function in a wide range of processes, including primary and secondary metabolism and meiosis. Other roles include regulation of genes involved in the stress response as well as pleiotropic drug resistance, as demonstrated in budding yeast and in human fungal pathogens. With the number of characterized zinc cluster proteins growing rapidly, it is becoming more and more apparent that they are important regulators of fungal physiology.

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“…Another possible explanation was that regulation of AF cluster gene expression was complex, and factors other than transcript levels of aflR and aflS were important in its regulation. afls transcript was thought to be dependent on aflR (Du et al, 2007;Ehrlich et al, 1999 andPrice et al, 2006). In contrast, Kong et al (2010) reported that the mRNA abundances of aflR and aflS genes in control were 1.11±0.24 and 0.18±0.05, respectively, while in experiment group were 0.28±0.03 and 0.024±0.005, respectively indicating that Bacillus megaterium could suppress the expression of these two genes.…”

Section: The Influence Of Lab On Aflr Gene Expression Responsible Formentioning

confidence: 95%

Anti-aflatoxigenic Effect of Some Lactobacillus Species on Aspergillus flavus by Using Real – Time - q PCR

2015

Egypt. J. Microbiol.

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Binding of the C6-zinc cluster protein, AFLR, to the promoters of aflatoxin pathway biosynthesis genes in Aspergillus parasiticus

Cited by 154 publications

References 24 publications

Comparison of the aflR gene sequences of strains in Aspergillus section Flavi

Comparison of the aflR gene sequences of strains in Aspergillus section Flavi

A Fungal Family of Transcriptional Regulators: the Zinc Cluster Proteins

Anti-aflatoxigenic Effect of Some Lactobacillus Species on Aspergillus flavus by Using Real – Time - q PCR

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