Regulation of the yeast CYT1 gene encoding cytochrome c1 by HAP1 and HAP2/3/4

1991 ◽  
Vol 11 (10) ◽  
pp. 4934-4942
Author(s):  
J C Schneider ◽  
L Guarente
Keyword(s):  
Cytochrome C ◽  
Mitochondrial Biogenesis ◽  
Binding Sites ◽  
Single Gene ◽  
Regulatory Region ◽  
Gene Encoding ◽  
High Affinity ◽  
High Affinity Site ◽  
Cytochrome C1 ◽  
The Difference

Mitochondrial biogenesis requires the coordinate induction of hundreds of genes that reside in the nucleus. We describe here a study of the regulation of the nuclear-encoded cytochrome c1 of the b-c1 complex. Unlike cytochrome c, which is encoded by two genes, CYC1 and CYC7, c1 is encoded by a single gene, CYT1. The regulatory region of the CYT1 promoter contains binding sites for the HAP1 and HAP2/3/4 transactivators that regulate CYC1. The binding of HAP1 to the CYT1 element was studied in detail and found to differ in two important respects from binding to the CYC1 element. First, while CYC1 contains two sites that bind HAP1 cooperatively, CYT1 has a single high-affinity site. Second, while the CYT1 site and the stronger HAP1-binding site of CYC1 share a large block of homology, the HAP1 footprints at these sites are offset by several nucleotides. We discuss how these differences in HAP1 binding might relate to the difference in the biology of cytochrome c and cytochrome c1.

scholarly journals Regulation of the yeast CYT1 gene encoding cytochrome c1 by HAP1 and HAP2/3/4.

1991 ◽  
Vol 11 (10) ◽  
pp. 4934-4942 ◽  
Author(s):  
J C Schneider ◽  
L Guarente
Keyword(s):  
Cytochrome C ◽  
Mitochondrial Biogenesis ◽  
Binding Sites ◽  
Single Gene ◽  
Regulatory Region ◽  
Gene Encoding ◽  
High Affinity ◽  
High Affinity Site ◽  
Cytochrome C1 ◽  
The Difference

Mitochondrial biogenesis requires the coordinate induction of hundreds of genes that reside in the nucleus. We describe here a study of the regulation of the nuclear-encoded cytochrome c1 of the b-c1 complex. Unlike cytochrome c, which is encoded by two genes, CYC1 and CYC7, c1 is encoded by a single gene, CYT1. The regulatory region of the CYT1 promoter contains binding sites for the HAP1 and HAP2/3/4 transactivators that regulate CYC1. The binding of HAP1 to the CYT1 element was studied in detail and found to differ in two important respects from binding to the CYC1 element. First, while CYC1 contains two sites that bind HAP1 cooperatively, CYT1 has a single high-affinity site. Second, while the CYT1 site and the stronger HAP1-binding site of CYC1 share a large block of homology, the HAP1 footprints at these sites are offset by several nucleotides. We discuss how these differences in HAP1 binding might relate to the difference in the biology of cytochrome c and cytochrome c1.

scholarly journals Interaction of phosphorylase b with eosin. Influence of substrate and effectors on eosin-enzyme complexes

1979 ◽  
Vol 181 (2) ◽  
pp. 309-320 ◽  
Author(s):  
N G Oikonomakos ◽  
T G Sotiroudis ◽  
A E Evangelopoulos
Keyword(s):  
Binding Sites ◽  
Dissociation Constants ◽  
Protein Molecule ◽  
Optical Probe ◽  
Rabbit Muscle ◽  
High Affinity ◽  
High Affinity Site ◽  
Dye Absorption ◽  
Competitive Model ◽  
The Difference

The interactions of rabbit muscle glycogen phosphorylase b with Eosin (2′,4′,5′,7′-tetrabromofluorescein) was studied. Eosin was found to be an effective inhibitor of the enzyme. The inhibition constants for the dye were estimated to be approx. 36 and 60 microM with respect to AMP and glucose 1-phosphate respectively. The binding of Eosin to phosphorylase b is accompanied by a red-shift of about 12 nm in the dye absorption-spectrum maximum, indicating low-polarity binding sites on the enzyme molecule for the dye. The absorbance in the difference absorption maximum at 537 nm was utilized to follow the conjugation of phosphorylase b with Eosin. Scatchard plots of the titration data revealed the existence of at least two classes of binding sites on the protein molecule for Eosin, and the dissociation constants measured in Tris/HCl buffer, pH 7.0 (IO.091), were 7.7 and 41.7 microM respectively. The influence of the substrates and effectors on Eosin-enzymes complexes was used to study the ligand-phosphorylase b interactions. IMP displaced the dye completely from the enzyme, indicating that there are two IMP-binding sites per phosphorylase b monomer. AMP binding to the enzyme with respect to Eosin concentration is of two types: a non-competitive one for the high-affinity site for AMP and a competitive one for the low-affinity site for the activator. The effects of glucose 6-phosphate, ATP, Pi and glycerol 2-phosphate in the system are in according dance with a partially competitive model. Glucoes 1-phosphate and UDP-glucose appear to affect only the high-affinity site for Eosin, whereas glucose and glycogen have no effect on Eosin-phosphorylase b complexes. Our results suggest that Eosin can be used as an efficient optical probe for studying the phosphorylase b system.

Global regulation of mitochondrial biogenesis in Saccharomyces cerevisiae: ABF1 and CPF1 play opposite roles in regulating expression of the QCR8 gene, which encodes subunit VIII of the mitochondrial ubiquinol-cytochrome c oxidoreductase

1992 ◽  
Vol 12 (6) ◽  
pp. 2872-2883
Author(s):  
J H de Winde ◽  
L A Grivell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Mitochondrial Biogenesis ◽  
Binding Sites ◽  
Promoter Region ◽  
S Phase ◽  
Negative Regulator ◽  
Global Regulation ◽  
Two Factors ◽  
Efficient Induction

The multifunctional DNA-binding proteins ABF1 and CPF1 bind in a mutually exclusive manner to the promoter region of the QCR8 gene, which encodes 11-kDa subunit VIII of the Saccharomyces cerevisiae mitochondrial ubiquinol-cytochrome c oxidoreductase (QCR). We investigated the roles that the two factors play in transcriptional regulation of this gene. To this end, the overlapping binding sites for ABF1 and CPF1 were mutated and placed in the chromosomal context of the QCR8 promoter. The effects on transcription of the QCR8 gene were analyzed both under steady-state conditions and during nutritional shifts. We found that ABF1 is required for repressed and derepressed transcription levels and for efficient induction of transcription upon escape from catabolite repression, independently of DNA replication. CPF1 acts as a negative regulator, modulating the overall induction response. Alleviation of repression through CPF1 requires passage through the S phase. Implications of these findings for the roles played by ABF1 and CPF1 in global regulation of mitochondrial biogenesis are discussed.

Uptake of 3,5,3′-l-tri-iodothyronine in human erythrocytes

1989 ◽  
Vol 121 (3) ◽  
pp. 585-591 ◽  
Author(s):  
K. Yamauchi ◽  
R. Horiuchi ◽  
H. Takikawa
Keyword(s):  
Binding Sites ◽  
Binding Capacity ◽  
Human Erythrocytes ◽  
The Other ◽  
Transport Pathway ◽  
High Affinity ◽  
High Affinity Site ◽  
Maximum Binding Capacity ◽  
Energy Dependent ◽  
Dependent Pathway

ABSTRACT The mechanisms of 3,5,3′-l-tri-iodothyronine (T3) uptake into human erythrocytes were examined. Purified membranes of human erythrocytes were shown to have two classes of T3-binding sites with one being a high-affinity site (dissociation constant, 59·2±17·8 nmol/l; maximum binding capacity, 344·3 ± 95·5 fmol/μg protein). Furthermore, it was shown that there were two pathways for T3 uptake in human erythrocytes; one was saturable, stereospecific (T3»thyroxine > 3,5,3′-d-tri-iodothyronine), energydependent and dominant at 15 °C; the other was not displaced by unlabelled T3 and was energyindependent but did not occur by passive diffusion. The former pathway which, it is suggested, is a receptor-mediated transport pathway, was inhibited by monodansylcadaverine, phloretin or oligomycin at 15 or 37 °C, but the latter pathway was not inhibited by these inhibitors. Our results strongly suggest that uptake of T3 by the energy-independent pathway became predominant over the energy-dependent pathway at 37 °C and accounted for 83% of total T3 uptake of human erythrocytes. Journal of Endocrinology (1989) 121, 585–591

scholarly journals Regulation of the yjjQ-bglJ Operon, Encoding LuxR-Type Transcription Factors, and the Divergent yjjP Gene by H-NS and LeuO

2007 ◽  
Vol 190 (3) ◽  
pp. 926-935 ◽  
Author(s):  
Thomas Stratmann ◽  
S. Madhusudan ◽  
Karin Schnetz
Keyword(s):  
Transcription Factors ◽  
Virulence Factor ◽  
Binding Sites ◽  
Regulatory Region ◽  
Gene Encoding ◽  
E Coli ◽  
Divergent Promoters ◽  
Nucleoprotein Complex ◽  
K 12 ◽  
Regulatory Sites

ABSTRACT The yjjQ and bglJ genes encode LuxR-type transcription factors conserved in several enterobacterial species. YjjQ is a potential virulence factor in avian pathogenic Escherichia coli. BglJ counteracts the silencing of the bgl (β-glucoside) operon by H-NS in E. coli K-12. Here we show that yjjQ and bglJ form an operon carried by E. coli K-12, whose expression is repressed by the histone-like nucleoid structuring (H-NS) protein. The LysR-type transcription factor LeuO counteracts this repression. Furthermore, the yjjP gene, encoding a membrane protein of unknown function and located upstream in divergent orientation to the yjjQ-bglJ operon, is likewise repressed by H-NS. Mapping of the promoters as well as the H-NS and LeuO binding sites within the 555-bp intergenic region revealed that H-NS binds to the center of the AT-rich regulatory region and distal to the divergent promoters. LeuO sites map to the center and to positions distal to the yjjQ promoters, while one LeuO binding site overlaps with the divergent yjjP promoter. This latter LeuO site is required for full derepression of the yjjQ promoters. The arrangement of regulatory sites suggests that LeuO restructures the nucleoprotein complex formed by H-NS. Furthermore, the data support the conclusion that LeuO, whose expression is likewise repressed by H-NS and which is a virulence factor in Salmonella enterica, is a master regulator that among other loci, also controls the yjjQ-bglJ operon and thus indirectly the presumptive targets of YjjQ and BglJ.

scholarly journals Powerful Induction of Divergent tgs1-Rv3131 Genes in Mycobacterium tuberculosis Is Mediated by DevR Interaction with a High-Affinity Site and an Adjacent Cryptic Low-Affinity Site

2009 ◽  
Vol 191 (19) ◽  
pp. 6075-6081 ◽  
Author(s):  
Santosh Chauhan ◽  
Jaya Sivaswami Tyagi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Binding Site ◽  
Binding Sites ◽  
Target Genes ◽  
Promoter Activation ◽  
Transcription Start ◽  
High Affinity ◽  
Synergistic Activation ◽  
Dnase I Footprinting ◽  
High Affinity Site

ABSTRACT DevR activates the transcription of ∼48 genes in response to hypoxia and other stresses and triggers metabolic downshift and dormancy development in Mycobacterium tuberculosis. tgs1 and Rv3131 encode triacylglycerol synthase and a putative nitroreductase, respectively, and both are members of the DevR regulon. This study aimed to understand how a single putative DevR binding site identified previously could sustain powerful induction of divergent tgs1-Rv3131 genes. DNase I footprinting revealed that phosphorylated DevR in fact binds to two sites symmetrically located at −42.5 and −63.5 bp from transcription start points of both genes. DevR first bound to the high-affinity site, P, and cooperatively recruited another DevR molecule to the secondary low-affinity site, S, to activate tgs1-Rv3131 transcription by ∼210- and ∼110-fold, respectively. The presence of a single P site significantly reduced activation of tgs1 expression and abolished Rv3131 activity, reinforcing the requirement of two binding sites for robust expression in both directions. P site inversion abolished tgs1 but not Rv3131 transcription despite DevR occupancy at both sites. The lack of tgs1 expression is most likely due to disruption of its −35 promoter element rather than inversion of the binding site per se. We conclude that (i) an overlap of a DevR binding site and −35 sequence is indispensable for promoter activation, (ii) DevR interaction with two binding sites is obligatory for synergistic activation of tgs1-Rv3131 promoters, and (iii) DevR interaction with binding sites of different affinities offers scope for temporal and differential expression of target genes.

Evaluation of the Binding to Fixed Platelets of Agonists and Antagonists of ADP-Induced Aggregation

1989 ◽  
Vol 62 (04) ◽  
pp. 1103-1106 ◽  
Author(s):  
Ashok K Agarwal ◽  
Narendra N Tandon ◽  
Nicholas J Greco ◽  
Noel J Cusack ◽  
G A Jamieson
Keyword(s):  
Binding Sites ◽  
Binding Assay ◽  
Relative Magnitude ◽  
Affinity Binding ◽  
Inhibitory Potency ◽  
Competitive Binding Assay ◽  
High Affinity ◽  
High Affinity Site ◽  
Purine Ring ◽  
Induced Aggregation

SummarySteady state binding of eleven different ADP analogues to formaldehyde-fixed platelets has been determined in a competitive binding assay using 3H-ADP. The compounds tested were the inactive analogues L-ADP and L-ATP; the agonists 2-chloroadenosine 5’-diphosphate, adenosine 5’-O-(2-thiodiphosphate)and the diastereoisomeric pair Sp-adenosine 5’-(1-thiodiphosphate) (Sp-ADP-α-S) and Rp-adenosine 5’-(1-thiodiphosphate) (Rp-ADP-α-S); and the antagonists adenosine 5’-O-thiomonophosphate, 2-chloroadenosine 5’-O-thiomonophosphate, 2-chloroadenosine 5’-triphoshate, and the diastereoisomeric pair 5’-(1-thiotriphosphate) (Sp-ATP-α-S) and Rp-adenosine 5’-(1-thiotriphosphate) (Rp-ATP-α-S). All compounds tested competed at the high affinity binding sites for ADP previously identified (Blood 1988; 71: 110-6) but in some cases competition could not be demonstrated at the low affinity sites because of the high nucleotide concentrations required. As a group, C2-substituted analogues bound less strongly (Ki >2 μM) than did the analogues without substituents in the purine ring (Ki <0.7 μM). With the pair of diastereoisomeric agonists Sp-ADP-α-S and Rp-ADP-α-S the Ki values at the high affinity site (210 nM and 560 nM) were of the same relative magnitude and in the same direction as their reported potencies as agonists (Ki 4 μM and 20 μM). With the diastereoisomeric antagonists Sp-ATP-α-S and Rp-ATP-α-S a similar relationship was seen between affinity (17 nM and 156 nM) and inhibitory potency (Ki 4 μM and 20 μM). These results may help to differentiate possible mechanisms in the interaction of ADP with its receptors.

scholarly journals Influence of starvation and clofibrate administration on oxidative phosphorylation by rat liver mitochondria

1980 ◽  
Vol 190 (1) ◽  
pp. 191-198 ◽  
Author(s):  
B K A Rasheed ◽  
S Chhabra ◽  
C K R Kurup
Keyword(s):  
Cytochrome C ◽  
Binding Sites ◽  
Liver Mitochondria ◽  
Potassium Ferricyanide ◽  
Rat Liver Mitochondria ◽  
Albino Rats ◽  
Succinate Dehydrogenase Activity ◽  
Whole Cells ◽  
High Affinity

Whole cells, homogenates and mitochondrial obtained from the livers of albino rats which were starved for 6 days or more showed a 50% decrease in oxidative activity. The decrease could be corrected by the addition of cytochrome c in vitro. The phosphorylative activity of mitochondria remained unaffected. The decrease in oxidative rate was not observed when starving animals were given the anti-hypercholesterolaemic drug clofibrate. The total cellular concentration of cytochrome c was not affected by starvation. However, the concentration of the pigment in hepatic mitochondria isolated from starving animals was less than half that in normal mitochondria. Clofibrate-treated animals did not show a decreased concentration of cytochrome c in hepatic mitochondria. Mitochondria isolated from starving animals, though deficient in cytochrome c, did not show any decrease in succinate dehydrogenase activity or in the rate of substrate-dependent reduction of potassium ferricyanide or attendant phosphorylation. In coupled mitochondria, ferricyanide may not accept electrons from the cytochrome c in the respiratory chain. Starvation decreases the concentration of high-affinity binding sites for cytochrome c on the mitochondrial membrane. The dissociation constant increases in magnitude.

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