scholarly journals Transcriptional Regulation of Genes Encoding the Selenium-Free [NiFe]-Hydrogenases in the Archaeon Methanococcus voltae Involves Positive and Negative Control Elements

Genetics ◽  
1999 ◽  
Vol 152 (4) ◽  
pp. 1335-1341
Author(s):  
Izabela Noll ◽  
Steffen Müller ◽  
Albrecht Klein

Abstract Methanococcus voltae harbors genetic information for two pairs of homologous [NiFe]-hydrogenases. Two of the enzymes contain selenocysteine, while the other two gene groups encode apparent isoenzymes that carry cysteinyl residues in the homologous positions. The genes coding for the selenium-free enzymes, frc and vhc, are expressed only under selenium limitation. They are transcribed out of a common intergenic region. A series of deletions made in the intergenic region localized a common negative regulatory element for the vhc and frc promoters as well as two activator elements that are specific for each of the two transcription units. Repeated sequences, partially overlapping the frc promoter, were also detected. Mutations in these repeated heptanucleotide sequences led to a weak induction of a reporter gene under the control of the frc promoters in the presence of selenium. This result suggests that the heptamer repeats contribute to the negative regulation of the frc transcription unit.

1993 ◽  
Vol 13 (6) ◽  
pp. 3686-3697 ◽  
Author(s):  
R L Young ◽  
S J Korsmeyer

bcl-2 mRNA is present at high levels in pre-B-cell lines but is down-regulated in most mature B-cell lines. To investigate the mechanisms responsible for its developmental control, we studied the regulation of bcl-2 expression in human B-lineage cell lines. Using nuclear run-on assays, we found that bcl-2 transcription decreases in parallel with levels of steady-state mRNA during B-cell development. To define cis-acting elements that regulate bcl-2 transcription, we analyzed the expression of transiently transfected promoter-reporter constructs. We identified a novel negative regulatory element (NRE) in the bcl-2 5'-untranslated region that decreased expression from the bcl-2 P1 promoter or heterologous promoters in a position-dependent fashion. The NRE functions in either orientation but contains distinct orientation-dependent subfragments. Additional analyses demonstrated that multiple, functionally redundant sequence elements mediate NRE activity. Though the bcl-2 NRE is active in pre-B- and mature B-cell lines, chromatin structure of the endogenous NRE differs in these cells, suggesting that its activity or effect may vary during B-cell development. Our results indicate that negative control of transcription initiated at the P1 promoter is an important determinant of the differential expression of bcl-2.


1993 ◽  
Vol 13 (6) ◽  
pp. 3686-3697
Author(s):  
R L Young ◽  
S J Korsmeyer

bcl-2 mRNA is present at high levels in pre-B-cell lines but is down-regulated in most mature B-cell lines. To investigate the mechanisms responsible for its developmental control, we studied the regulation of bcl-2 expression in human B-lineage cell lines. Using nuclear run-on assays, we found that bcl-2 transcription decreases in parallel with levels of steady-state mRNA during B-cell development. To define cis-acting elements that regulate bcl-2 transcription, we analyzed the expression of transiently transfected promoter-reporter constructs. We identified a novel negative regulatory element (NRE) in the bcl-2 5'-untranslated region that decreased expression from the bcl-2 P1 promoter or heterologous promoters in a position-dependent fashion. The NRE functions in either orientation but contains distinct orientation-dependent subfragments. Additional analyses demonstrated that multiple, functionally redundant sequence elements mediate NRE activity. Though the bcl-2 NRE is active in pre-B- and mature B-cell lines, chromatin structure of the endogenous NRE differs in these cells, suggesting that its activity or effect may vary during B-cell development. Our results indicate that negative control of transcription initiated at the P1 promoter is an important determinant of the differential expression of bcl-2.


1993 ◽  
Vol 13 (1) ◽  
pp. 63-71 ◽  
Author(s):  
G Yu ◽  
J S Fassler

The Ty transposable elements of Saccharomyces cerevisiae consist of a single large transcription unit whose expression is controlled by a combination of upstream and downstream regulatory sequences. Errede (B. Errede, Mol. Cell. Biol. 13:57-62, 1993) has shown that among the downstream control sequences is a binding site for the transcription factor, MCM1. A small restriction fragment containing the Ty1 MCM1-binding site exhibits very weak activation of heterologous gene expression. The absence of SPT13 (GAL11) causes a dramatic increase in activity directed by these sequences. This effect is mediated through the MCM1-binding site itself. MCM1 mRNA and protein levels, as well as its affinity for its binding site, are unchanged in the absence of SPT13. Our results suggest that SPT13 has a role in the negative control of MCM1 activity that is likely to be posttranslational. A role for SPT13 in the negative regulation of the activity of the Ty1 MCM1-binding site is consistent with our previous proposal that spt13-mediated suppression of Ty insertion mutations could be attributed to the loss of negative regulation of genes adjacent to Ty elements.


1991 ◽  
Vol 11 (3) ◽  
pp. 1334-1343
Author(s):  
R Paciucci ◽  
A Pellicer

The 5' flanking region of the mouse N-ras gene was investigated to determine the elements governing transcriptional activity of the gene. The promoter did not contain typical TATA or CCAAT boxes, and according to primer extension and RNase protection analyses, transcription started at several sites. These assays also confirmed the short nucleotide distance interposed between the N-ras transcription unit and the previously described upstream unr gene. Chromatin studies performed by digestion of nuclei with DNase I revealed the presence of four hypersensitive sites: a, b, c, and d. Deletion mutagenesis of the 5' flanking region revealed sequences responsible for both promotion and inhibition of transcription. These sequences resided within 230 bp upstream of the transcription initiation site. Hypersensitive site b colocalized with the 76-bp segment with promoter activity. The negative regulatory element at position -180 colocalized with hypersensitive site a, was active on the N-ras promoter in stable as well as transient assays, and down-regulated the heterologous herpes simplex virus thymidine kinase promoter. Footprint analysis and in vivo transfection-competition experiments indicated that a trans-acting factor is responsible for the negative effect on transcription. The interaction between the cis-acting negative regulatory element and the promoter region may play a role in the tissue- and developmental-stage-specific patterns of expression of the N-ras gene.


1993 ◽  
Vol 13 (1) ◽  
pp. 63-71
Author(s):  
G Yu ◽  
J S Fassler

The Ty transposable elements of Saccharomyces cerevisiae consist of a single large transcription unit whose expression is controlled by a combination of upstream and downstream regulatory sequences. Errede (B. Errede, Mol. Cell. Biol. 13:57-62, 1993) has shown that among the downstream control sequences is a binding site for the transcription factor, MCM1. A small restriction fragment containing the Ty1 MCM1-binding site exhibits very weak activation of heterologous gene expression. The absence of SPT13 (GAL11) causes a dramatic increase in activity directed by these sequences. This effect is mediated through the MCM1-binding site itself. MCM1 mRNA and protein levels, as well as its affinity for its binding site, are unchanged in the absence of SPT13. Our results suggest that SPT13 has a role in the negative control of MCM1 activity that is likely to be posttranslational. A role for SPT13 in the negative regulation of the activity of the Ty1 MCM1-binding site is consistent with our previous proposal that spt13-mediated suppression of Ty insertion mutations could be attributed to the loss of negative regulation of genes adjacent to Ty elements.


1991 ◽  
Vol 11 (3) ◽  
pp. 1334-1343 ◽  
Author(s):  
R Paciucci ◽  
A Pellicer

The 5' flanking region of the mouse N-ras gene was investigated to determine the elements governing transcriptional activity of the gene. The promoter did not contain typical TATA or CCAAT boxes, and according to primer extension and RNase protection analyses, transcription started at several sites. These assays also confirmed the short nucleotide distance interposed between the N-ras transcription unit and the previously described upstream unr gene. Chromatin studies performed by digestion of nuclei with DNase I revealed the presence of four hypersensitive sites: a, b, c, and d. Deletion mutagenesis of the 5' flanking region revealed sequences responsible for both promotion and inhibition of transcription. These sequences resided within 230 bp upstream of the transcription initiation site. Hypersensitive site b colocalized with the 76-bp segment with promoter activity. The negative regulatory element at position -180 colocalized with hypersensitive site a, was active on the N-ras promoter in stable as well as transient assays, and down-regulated the heterologous herpes simplex virus thymidine kinase promoter. Footprint analysis and in vivo transfection-competition experiments indicated that a trans-acting factor is responsible for the negative effect on transcription. The interaction between the cis-acting negative regulatory element and the promoter region may play a role in the tissue- and developmental-stage-specific patterns of expression of the N-ras gene.


2002 ◽  
Vol 76 (12) ◽  
pp. 5993-6003 ◽  
Author(s):  
Sarah A. Cumming ◽  
Claire E. Repellin ◽  
Maria McPhillips ◽  
Jonathan C. Radford ◽  
J. Barklie Clements ◽  
...  

ABSTRACT The papillomavirus life cycle is tightly linked to epithelial cell differentiation. Production of virus capsid proteins is restricted to the most terminally differentiated keratinocytes in the upper layers of the epithelium. However, mRNAs encoding the capsid proteins can be detected in less-differentiated cells, suggesting that late gene expression is controlled posttranscriptionally. Short sequence elements (less than 80 nucleotides in length) that inhibit gene expression in undifferentiated epithelial cells have been identified in the late 3′ untranslated regions (UTRs) of several papillomaviruses, including the high-risk mucosal type human papillomavirus type 16 (HPV-16). Here we show that closely related high-risk mucosal type HPV-31 also contains elements that can act to repress gene expression in undifferentiated epithelial cells. However, the HPV-31 negative regulatory element is surprisingly complex, comprising a major inhibitory element of approximately 130 nucleotides upstream of the late polyadenylation site and a minor element of approximately 110 nucleotides mapping downstream. The first 60 nucleotides of the major element have 68% identity to the negative regulatory element of HPV-16, and these elements bind the same cellular proteins, CstF-64, U2AF65, and HuR. The minor inhibitory element binds some cellular proteins in common with the major inhibitory element, though it also binds certain proteins that do not bind the upstream element.


Virology ◽  
1992 ◽  
Vol 186 (1) ◽  
pp. 133-147 ◽  
Author(s):  
Mauro Giacca ◽  
Maria Ines Gutierrez ◽  
Stefano Menzo ◽  
Fabrizio D'Adda Di Fagagna ◽  
Arturo Flaschi

2001 ◽  
Vol 281 (4) ◽  
pp. G865-G869 ◽  
Author(s):  
Steven D. Clarke

This review addresses the hypothesis that polyunsaturated fatty acids (PUFA), particularly those of the n-3 family, play pivotal roles as “fuel partitioners” in that they direct fatty acids away from triglyceride storage and toward oxidation and they enhance glucose flux to glycogen. In doing this, PUFA may reduce the risk of enhanced cellular apoptosis associated with excessive cellular lipid accumulation. PUFA exert their beneficial effects by upregulating the expression of genes encoding proteins involved in fatty acid oxidation while simultaneously downregulating genes encoding proteins of lipid synthesis. PUFA govern oxidative gene expression by activating the transcription factor peroxisome proliferator-activated receptor-α. PUFA suppress lipogenic gene expression by reducing the nuclear abundance and DNA binding affinity of transcription factors responsible for imparting insulin and carbohydrate control to lipogenic and glycolytic genes. In particular, PUFA suppress the nuclear abundance and expression of sterol regulatory element binding protein-1 and reduce the DNA binding activities of nuclear factor Y, stimulatory protein 1, and possibly hepatic nuclear factor-4. Collectively, the studies discussed suggest that the fuel “repartitioning” and gene expression actions of PUFA should be considered among the criteria used in defining the dietary needs of n-6 and n-3 fatty acids and in establishing the dietary ratio of n-6 to n-3 fatty acids needed for optimum health benefit.


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