Sulfur-regulated control of the met-2 gene of Neurospora crassa encoding cystathionine β-lyaseReportar como inadecuado

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BMC Research Notes

, 6:259

First Online: 08 July 2013Received: 09 January 2013Accepted: 03 July 2013DOI: 10.1186-1756-0500-6-259

Cite this article as: Reveal, B.S. & Paietta, J.V. BMC Res Notes 2013 6: 259. doi:10.1186-1756-0500-6-259


BackgroundCystathionine 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.

FindingsThe 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.

ConclusionsIn 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.

KeywordsCystathionine β-lyase met-2 Transsulfuration Sulfur gene regulation CYS3 regulator Neurospora crassa Electronic supplementary materialThe online version of this article doi:10.1186-1756-0500-6-259 contains supplementary material, which is available to authorized users.

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Autor: Brad S Reveal - John V Paietta


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