scholarly journals Transcriptional Regulation of the Cellobiose Operon of Streptococcus mutans

2009 ◽  
Vol 191 (7) ◽  
pp. 2153-2162 ◽  
Author(s):  
Lin Zeng ◽  
Robert A. Burne
Keyword(s):  
Transcriptional Regulation ◽  
Streptococcus Mutans ◽  
Transcriptional Activation ◽  
Catabolite Repression ◽  
Critical Role ◽  
Gene Promoters ◽  
Direct Role ◽  
Regulatory Domains ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

ABSTRACT The ability of Streptococcus mutans to catabolize cellobiose, a β-linked glucoside generated during the hydrolysis of cellulose, is shown to be regulated by a transcriptional regulator, CelR, which is encoded by an operon with a phospho-β-glucosidase (CelA) and a cellobiose-specific sugar phosphotransferase system (PTS) permease (EIICel). The roles of CelR, EIICel components, and certain fructose/mannose-PTS permeases in the transcriptional regulation of the cel locus were analyzed. The results revealed that (i) the celA and celB (EIIBCel) gene promoters require CelR for transcriptional activation in response to cellobiose, but read-through from the celA promoter contributes to expression of the EIICel genes; (ii) the EIICel subunits were required for growth on cellobiose and for transcriptional activation of the cel genes; (iii) CcpA plays little direct role in catabolite repression of the cel regulon, but loss of specific PTS permeases alleviated repression of cel genes in the presence of preferred carbohydrates; and (iv) glucose could induce transcription of the cel regulon when transported by EIICel. CelR derivatives containing amino acid substitutions for five conserved histidine residues in two PTS regulatory domains and an EIIA-like domain also provided important insights regarding the function of this regulator. Based on these data, a model for the involvement of PTS permeases and the general PTS proteins enzyme I and HPr was developed that reveals a critical role for the PTS in CcpA-independent catabolite repression and induction of cel gene expression in S. mutans.

Transcriptional regulation by Fos and Jun in vitro: interaction among multiple activator and regulatory domains

1991 ◽  
Vol 11 (7) ◽  
pp. 3624-3632
Author(s):  
C Abate ◽  
D Luk ◽  
T Curran
Keyword(s):  
Transcriptional Regulation ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Regulatory Function ◽  
Activation Domain ◽  
Regulatory Domains ◽  
Heterodimeric Complex ◽  
Transcriptional Stimulation

The proteins encoded by the proto-oncogenes c-fos and c-jun (Fos and Jun, respectively) form a heterodimeric complex that regulates transcription by interacting with the DNA-regulatory element known as the activator protein 1 (AP-1) binding site. Fos and Jun are members of a family of related transcription factors that dimerize via a leucine zipper structure and interact with DNA through a bipartite domain formed between regions of each protein that are rich in basic amino acids. Here we have defined other domains in the Fos-Jun heterodimer that contribute to transcriptional function in vitro. Although DNA-binding specificity is mediated by the leucine zipper and basic regions, Jun also contains a proline- and glutamine-rich region that functions as an ancillary DNA-binding domain but does not contribute directly to transcriptional activation. Transcriptional stimulation in vitro was associated with two regions in Fos and a single N-terminal activation domain in Jun. These activator regions were capable of operating independently; however, they appear to function cooperatively in the heterodimeric complex. The activity of these domains was modulated by inhibitory regions in Fos and Jun that repressed transcription in vitro. In the context of the heterodimer, the Jun activation domain was the major contributor to transcriptional stimulation and the inhibitory regions in Fos were the major contributors to transcriptional repression in vitro. Potentially, the inhibitory domains could serve a regulatory function in vivo. Thus, transcriptional regulation by the Fos-Jun heterodimer results from a complex integration of multiple activator and regulatory domains.

scholarly journals Regulation of HIS4 expression by the Saccharomyces cerevisiae SIN4 transcriptional regulator.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 103-114 ◽  
Author(s):  
Y W Jiang ◽  
D J Stillman
Keyword(s):  
Transcriptional Regulation ◽  
Binding Site ◽  
Chromatin Structure ◽  
Transcriptional Activation ◽  
Transcriptional Regulator ◽  
Promoter Mutation ◽  
Direct Role ◽  
Gene Functions ◽  
Yeast Genes ◽  
His4 Gene

Abstract The yeast SIN4 gene functions in the transcriptional activation and repression of diverse yeast genes. Previous experiments suggest a sin4 mutation affects chromatin structure and thus alters transcriptional regulation. In this report we show that SIN4 is required for full expression of the HIS4, Ty1, and MAT alpha genes, in addition to the previously described SIN4-dependence of CTS1 expression. All of these genes contain within their promoters a binding site for the Rap1p transcriptional regulator. However, SIN4 does not play a direct role either in transcriptional activation or repression by Rap1p. The HIS4 gene can be activated by either of two pathways, the basal or the inducible pathway, and experiments are described that show that a sin4 mutation affects both pathways. It was shown previously that mutation of the Rap1p binding site in the HIS4 promoter causes a similar effect on HIS4 expression and that this promoter mutation also causes a change in chromatin structure. The SNF2/SWI2 gene is also required for full HIS4 expression, and we show that a sin4 snf2 double mutant is not synergistic compared to either single mutant. We show that nucleosomes are positioned at the HIS4 promoter and that this positioning is disrupted in a snf2 mutant but not in a sin4 mutant. These findings suggest that SIN4 plays a distinct role in transcriptional regulation.

scholarly journals Transcriptional regulation by Fos and Jun in vitro: interaction among multiple activator and regulatory domains.

1991 ◽  
Vol 11 (7) ◽  
pp. 3624-3632 ◽  
Author(s):  
C Abate ◽  
D Luk ◽  
T Curran
Keyword(s):  
Transcriptional Regulation ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Regulatory Function ◽  
Activation Domain ◽  
Regulatory Domains ◽  
Heterodimeric Complex ◽  
Transcriptional Stimulation

The proteins encoded by the proto-oncogenes c-fos and c-jun (Fos and Jun, respectively) form a heterodimeric complex that regulates transcription by interacting with the DNA-regulatory element known as the activator protein 1 (AP-1) binding site. Fos and Jun are members of a family of related transcription factors that dimerize via a leucine zipper structure and interact with DNA through a bipartite domain formed between regions of each protein that are rich in basic amino acids. Here we have defined other domains in the Fos-Jun heterodimer that contribute to transcriptional function in vitro. Although DNA-binding specificity is mediated by the leucine zipper and basic regions, Jun also contains a proline- and glutamine-rich region that functions as an ancillary DNA-binding domain but does not contribute directly to transcriptional activation. Transcriptional stimulation in vitro was associated with two regions in Fos and a single N-terminal activation domain in Jun. These activator regions were capable of operating independently; however, they appear to function cooperatively in the heterodimeric complex. The activity of these domains was modulated by inhibitory regions in Fos and Jun that repressed transcription in vitro. In the context of the heterodimer, the Jun activation domain was the major contributor to transcriptional stimulation and the inhibitory regions in Fos were the major contributors to transcriptional repression in vitro. Potentially, the inhibitory domains could serve a regulatory function in vivo. Thus, transcriptional regulation by the Fos-Jun heterodimer results from a complex integration of multiple activator and regulatory domains.

scholarly journals Mediator is broadly recruited to gene promoters via a Tail-independent mechanism

2021 ◽  
Author(s):  
Linda Warfield ◽  
Rafal Donczew ◽  
Lakshmi Mahendrawada ◽  
Steven Hahn
Keyword(s):  
Transcriptional Regulation ◽  
Transcription Initiation ◽  
Binding Domain ◽  
Small Subset ◽  
Gene Promoters ◽  
Direct Role ◽  
Functional Link ◽  
Genome Wide ◽  
Independent Mechanism ◽  
Assembly Pathways

Mediator (MED) is a conserved factor with important roles in both basal and activated transcription. It is believed that MED plays a direct role in transcriptional regulation at most genes by functionally bridging enhancers and promoters. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. We find that MED Tail and activator-mediated MED recruitment regulate only a small subset of genes. At most genes, MED bypasses the UAS and is directly recruited to promoters to facilitate transcription initiation. Our results define three classes of genes that differ in PIC assembly pathways and the requirements for MED Tail, SAGA, TFIID and BET factors Bdf1/2. We also find that the depletion of the MED middle module subunit Med7 mimics inactivation of Tail, suggesting a functional link. Our combined results have broad implications for the roles of MED, other coactivators, and mechanisms of transcriptional regulation at different gene classes.

Regulation of cellulase from Ruminococcus

1972 ◽  
Vol 18 (3) ◽  
pp. 347-353 ◽  
Author(s):  
M. C. Fusee ◽  
J. M. Leatherwood
Keyword(s):  
Enzyme Activity ◽  
Cell Growth ◽  
Catabolite Repression ◽  
Specific Activity ◽  
Product Inhibition ◽  
Enzyme Synthesis ◽  
Energy Sources ◽  
Low Concentrations ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

The regulation of cellulase was examined in Ruminococcus albus and R. flavefaciens. Hydrolysis of cellulose, as shown by the formation of clear zones around the colonies of bacteria grown in cellulose-agar roll tubes, was inhibited by moderate levels of cellobiose. An intermediate in the metabolism of cellobiose may be responsible for the inhibition since strains which can use either sucrose or lactose were similarly inhibited by these energy sources. The inhibition of cellulase was examined in relation to either repression of enzyme synthesis or product inhibition of the enzyme activity. There was no inhibition by cellobiose added either to the routine enzymatic assay or to assays using low concentrations of carboxymethylcellulose. A repression mechanism was indicated by the decrease in specific activity of cultures grown in higher concentrations of cellobiose. The specific activity was calculated as the enzymatic activity on carboxymethylcellulose with respect to cell growth. The mechanism of repression was not distinguished between the model proposed by Jacob and Monod and catabolite repression. The growth of R. albus cultured in cellobiose–cellulose liquid medium exhibited a diauxic pattern similar to that described by Monod.

Immobilized Nanoparticles-Mediated Enzymatic Hydrolysis of Cellulose for Clean Sugar Production: A Novel Approach

2019 ◽  
Vol 15 (3) ◽  
pp. 296-303 ◽  
Author(s):  
Swapnil Gaikwad ◽  
Avinash P. Ingle ◽  
Silvio Silverio da Silva ◽  
Mahendra Rai
Keyword(s):  
Catalytic Activity ◽  
Enzymatic Hydrolysis ◽  
Immobilized Enzyme ◽  
Free Enzyme ◽  
Magnetic Nanomaterials ◽  
Sugar Production ◽  
Cellulase Enzyme ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

Background: Enzymatic hydrolysis of cellulose is an expensive approach due to the high cost of an enzyme involved in the process. The goal of the current study was to apply magnetic nanomaterials as a support for immobilization of enzyme, which helps in the repeated use of immobilized enzyme for hydrolysis to make the process cost-effective. In addition, it will also provide stability to enzyme and increase its catalytic activity. Objective: The main aim of the present study is to immobilize cellulase enzyme on Magnetic Nanoparticles (MNPs) in order to enable the enzyme to be re-used for clean sugar production from cellulose. Methods: MNPs were synthesized using chemical precipitation methods and characterized by different techniques. Further, cellulase enzyme was immobilized on MNPs and efficacy of free and immobilized cellulase for hydrolysis of cellulose was evaluated. Results: Enzymatic hydrolysis of cellulose by immobilized enzyme showed enhanced catalytic activity after 48 hours compared to free enzyme. In first cycle of hydrolysis, immobilized enzyme hydrolyzed the cellulose and produced 19.5 ± 0.15 gm/L of glucose after 48 hours. On the contrary, free enzyme produced only 13.7 ± 0.25 gm/L of glucose in 48 hours. Immobilized enzyme maintained its stability and produced 6.15 ± 0.15 and 3.03 ± 0.25 gm/L of glucose in second and third cycle, respectively after 48 hours. Conclusion: This study will be very useful for sugar production because of enzyme binding efficiency and admirable reusability of immobilized enzyme, which leads to the significant increase in production of sugar from cellulosic materials.

In Situ Microscopy for In-line Monitoring of the Enzymatic Hydrolysis of Cellulose

2013 ◽  
Vol 85 (17) ◽  
pp. 8121-8126 ◽  
Author(s):  
Britta Opitz ◽  
Andreas Prediger ◽  
Christian Lüder ◽  
Marrit Eckstein ◽  
Lutz Hilterhaus ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

Enhanced Hydrolysis of Cellulose to Reducing Sugars on Kaolinte Clay Activated by Mineral Acid

2021 ◽  
Author(s):  
Yuxiao Dong ◽  
Dongshen Tong ◽  
Laibin Ren ◽  
Xingtao Chen ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Reducing Sugars ◽  
Mineral Acid ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

Role and significance of beta-glucosidases in the hydrolysis of cellulose for bioethanol production

2013 ◽  
Vol 127 ◽  
pp. 500-507 ◽  
Author(s):  
Reeta Rani Singhania ◽  
Anil Kumar Patel ◽  
Rajeev K. Sukumaran ◽  
Christian Larroche ◽  
Ashok Pandey
Keyword(s):  
Bioethanol Production ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of
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