Sulfur-regulated control of the met-2+ gene of Neurospora crassa encoding cystathionine β-lyase

BMC Research Notes

John V Paietta¹  Brad S Reveal¹ 

[1] Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH 45435, USA

关键词: Neurospora crassa;    CYS3 regulator;    Sulfur gene regulation;    Transsulfuration;    met-2⁺;    Cystathionine β-lyase;   

Others  :  1142252
DOI  :  10.1186/1756-0500-6-259

 received in 2013-01-09, accepted in 2013-07-03,  发布年份 2013

【 摘 要 】

Background

Cystathionine β-lyase performs an essential role in the transsulfuration pathway by its primary reaction of forming homocysteine from cystathionine. Understanding how the Neurospora crassa met-2⁺ gene, which encodes cystathionine β-lyase, is regulated is important in determining the basis of the cellular control of transsulfuration. The aim of this study was to determine the nature of a potential regulatory connection of met-2⁺ to the Neurospora sulfur regulatory network.

Findings

The cystathionine β-lyase (met-2⁺) gene was cloned by the identification of a cosmid genomic clone capable of transforming a met-2 mutant to methionine prototrophy and subsequently characterized. The gene contains a single intron and encodes a protein of 457 amino acids with conserved residues predicted to be important for catalysis and pyridoxal-5′-phosphate co-factor binding. The expression of met-2⁺ in wild-type N. crassa increased 3.1-fold under sulfur-limiting growth conditions as compared to the transcript levels seen under high sulfur growth conditions (i.e., repressing conditions). In a Δcys-3 strain, met-2⁺ transcript levels were substantially reduced under either low- or high-sulfur growth conditions. In addition, the presence of CYS3 activator binding sites on the met-2⁺ promoter was demonstrated by gel mobility shift assays.

Conclusions

In this report, we demonstrate the sulfur-regulated expression of the met-2⁺ gene and confirm its connection to the N. crassa sulfur regulatory circuit by the reduced expression observed in a Δcys-3 mutant and the in vitro detection of CYS3 binding sites in the met-2⁺ promoter. The data further adds to our understanding of the regulatory dynamics of transsulfuration.

【 授权许可】

   
2013 Reveal and Paietta; licensee BioMed Central Ltd.

【 图 表 】

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