Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cys-3+ gene of Neurospora crassa encodes a bZIP (basic region-leucine zipper) regulatory protein that is essential for sulfur structural gene expression (e.g., ars-1+). Nuclear transcription assays confirmed that cys-3+ was under sulfur-regulated transcriptional control and that cys-3+ transcription was constitutive in sulfur controller (scon)-negative regulator mutants. Given these results, I have tested whether expression of cys-3+ under high-sulfur (repressing) conditions was sufficient to induce sulfur gene expression. The N. crassa beta-tubulin (tub) promoter was fused to the cys-3+ coding segment and used to transform a cys-3 deletion mutant. Function of the tub::cys-3 fusion in homokaryotic transformants grown under high-sulfur conditions was confirmed by Northern (RNA) and Western immunoblot analysis. The tub::cys-3 transformants showed arylsulfatase gene expression under normally repressing high-sulfur conditions. A tub::cys-3ts fusion encoding a temperature-sensitive CYS3 protein was used to confirm that the induced structural gene expression was due to CYS3 protein function. Constitutive CYS3 production did not induce scon-2+ expression under repressing conditions. In addition, a cys-3 promoter fusion to lacZ showed that CYS3 production was sufficient to induce its own expression and provides in vivo evidence for autoregulation. Finally, an apparent inhibitory effect observed with a strain carrying a point mutation at the cys-3 locus was examined by in vitro heterodimerization studies. These results support an interpretation of CYS3 as a transcriptional activator whose regulation is a crucial control point in the signal response pathway triggered by sulfur limitation.
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PMID:Production of the CYS3 regulator, a bZIP DNA-binding protein, is sufficient to induce sulfur gene expression in Neurospora crassa. 153 30

In Chlamydomonas reinhardtii, cytochrome c6 (cyt c6) is synthesized only under conditions of copper deficiency when plastocyanin cannot be synthesized. In previous work, the copper-responsive regulation of cyt c6 synthesis was demonstrated to occur by control of transcription, with no contribution from post-transcriptional processes. To understand the mechanism underlying its regulation, the genomic DNA encoding cyt c6 (Cyc6) was analyzed for the presence of copper-responsive elements. Sequences lying between positions -127 and -7 with respect to the start site of transcription were found to be sufficient to confer copper-responsive expression on either a promoterless or a minimal beta-tubulin promoter-driven (arylsulfatase-encoding) reporter gene. Analysis of this 120-bp fragment indicated that copper-responsive elements lie in two distinct regions (between -110 to -56 and -127 to -109). ATG fusions between copper-insensitive promoters and the coding plus 3' untranslated region of the Cyc6 gene resulted in the accumulation of cyt c6 in copper-supplemented medium; this confirms earlier studies indicating a lack of post-transcriptional control in this copper-responsive pathway. In the context of a constitutive promoter (derived from the beta-tubulin gene), each region was found to function as an activator of transcription in copper-deficient cells, and the metal specificity of the response of reporter genes containing either one or both regions was identical to that of the endogenous Cyc6 gene. The copper-responsive synthesis of cyt c6 is thus attributed to these two 5' upstream sequences.
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PMID:Two copper-responsive elements associated with the Chlamydomonas Cyc6 gene function as targets for transcriptional activators. 778 Mar 10

In Chlamydomonas reinhardtii, the expression of the Nia1 gene encoding NAD(P)H nitrate reductase is controlled at the transcriptional level, positively by light and negatively by ammonium. Previous work has shown that the region -279 to +269 with respect to the start site of transcription was sufficient to confer regulated expression of a promoterless arylsulfatase (Ars) reporter gene. To understand the mechanisms underlying this regulation, the -279 to +2 sequence was analysed for the presence of ammonium-responsive elements using either pJD54 (promoterless Ars gene) or pJD100 (minimal beta-tubulin promoter-driven Ars gene). The region lying between -195 and -120 was shown to be dispensable. Essential responsive elements were found in four distinct regions between -231 and -219, -120 and -100, -76 and -65 and -33 and -8. Each of these sequences is required for maximal expression in the absence of ammonium and a conserved GGA/TAGGGT motif is present in two of these regions. Several deletions within the region -33 to -77 were shown to partially relieve the transformants from the negative effect of ammonium. These experiments demonstrate that Nia1 expression is promoted by at least four elements between -231 and -8 and suggest that part of the repression by ammonium takes place through a proximal element located in the -51 to -33 sequence.
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PMID:Identification of short promoter regions involved in the transcriptional expression of the nitrate reductase gene in Chlamydomonas reinhardtii. 1128 12

In Chlamydomonas reinhardtii, the expression of the Nia1 gene encoding NAD(P)H nitrate reductase is controlled at the transcriptional level, positively by light and nitrate and negatively by ammonium. The sequences lying between positions -247 and -25 with respect to the start site of transcription were analyzed for the presence of regulatory elements using an arylsulfatase reporter gene ( Ars) fused to a minimal beta-tubulin promoter. An 84-bp sequence resulting from the joining of two partially homologous regions (-231 to -201 and -77 to -25) was shown to be necessary and sufficient to ensure activation and repression of the reporter gene. Interestingly, this shortened construct overexpressed the Ars gene in cells grown in nitrate-containing medium, relative to the construct bearing the complete -247 to -25 sequence. The 223-bp sequence was subjected to linker-scan analyses in the two regions of interest (-231 to -201 and -77 to -25). Most mutations introduced into this 84-bp sequence were shown to affect transcriptional activation on nitrate. Many of them also resulted in significantly increased arylsulfatase levels in cultures grown on ammonium. We therefore propose that the two regions act as bifunctional elements, stimulating or inhibiting the activity of the Nia1 promoter depending on the nature of the nitrogen source.
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PMID:Two short regions of the promoter are essential for activation and repression of the nitrate reductase gene in Chlamydomonas reinhardtii. 1224 97