scholarly journals Negative regulation of the Nrf1 transcription factor by its N-terminal domain is independent of Keap1: Nrf1, but not Nrf2, is targeted to the endoplasmic reticulum

2006 ◽  
Vol 399 (3) ◽  
pp. 373-385 ◽  
Author(s):  
Yiguo Zhang ◽  
Dorothy H. Crouch ◽  
Masayuki Yamamoto ◽  
John D. Hayes
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Amino Acid ◽  
Fusion Protein ◽  
Nuclear Staining ◽  
Wild Type ◽  
Cytoplasmic Staining ◽  
Acidic Domain ◽  
Terminal Domain

Nrf1 (nuclear factor-erythroid 2 p45 subunit-related factor 1) and Nrf2 regulate ARE (antioxidant response element)-driven genes. At its N-terminal end, Nrf1 contains 155 additional amino acids that are absent from Nrf2. This 155-amino-acid polypeptide includes the N-terminal domain (NTD, amino acids 1–124) and a region (amino acids 125–155) that is part of acidic domain 1 (amino acids 125–295). Within acidic domain 1, residues 156–242 share 43% identity with the Neh2 (Nrf2-ECH homology 2) degron of Nrf2 that serves to destabilize this latter transcription factor through an interaction with Keap1 (Kelch-like ECH-associated protein 1). We have examined the function of the 155-amino-acid N-terminal polypeptide in Nrf1, along with its adjacent Neh2-like subdomain. Activation of ARE-driven genes by Nrf1 was negatively controlled by the NTD (N-terminal domain) through its ability to direct Nrf1 to the endoplasmic reticulum. Ectopic expression of wild-type Nrf1 and mutants lacking either the NTD or portions of its Neh2-like subdomain into wild-type and mutant mouse embryonic fibroblasts indicated that Keap1 controls neither the activity of Nrf1 nor its subcellular distribution. Immunocytochemistry showed that whereas Nrf1 gave primarily cytoplasmic staining that was co-incident with that of an endoplasmic-reticulum marker, Nrf2 gave primarily nuclear staining. Attachment of the NTD from Nrf1 to the N-terminus of Nrf2 produced a fusion protein that was redirected from the nucleus to the endoplasmic reticulum. Although this NTD–Nrf2 fusion protein exhibited less transactivation activity than wild-type Nrf2, it was nevertheless still negatively regulated by Keap1. Thus Nrf1 and Nrf2 are targeted to different subcellular compartments and are negatively regulated by distinct mechanisms.

scholarly journals N-terminal acetylation of the yeast Derlin Der1 is essential for Hrd1 ubiquitin-ligase activity toward luminal ER substrates

2013 ◽  
Vol 24 (7) ◽  
pp. 890-900 ◽  
Author(s):  
Dimitrios Zattas ◽  
David J. Adle ◽  
Eric M. Rubenstein ◽  
Mark Hochstrasser
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Fusion Protein ◽  
Protein Degradation ◽  
Ubiquitin Ligase ◽  
Ubiquitin Ligases ◽  
Recent Analysis ◽  
Specific Class ◽  
Wild Type ◽  
Ubiquitin Ligase Activity

Two conserved ubiquitin ligases, Hrd1 and Doa10, mediate most endoplasmic reticulum–associated protein degradation (ERAD) in yeast. Degradation signals (degrons) recognized by these ubiquitin ligases remain poorly characterized. Doa10 recognizes the Deg1 degron from the MATα2 transcription factor. We previously found that deletion of the gene (NAT3) encoding the catalytic subunit of the NatB N-terminal acetyltransferase weakly stabilized a Deg1-fusion protein. By contrast, a recent analysis of several MATα2 derivatives suggested that N-terminal acetylation of these proteins by NatB was crucial for recognition by Doa10. We now analyze endogenous MATα2 degradation in cells lacking NatB and observe minimal perturbation relative to wild-type cells. However, NatB mutation strongly impairs degradation of ER-luminal Hrd1 substrates. This unexpected defect derives from a failure of Der1, a Hrd1 complex subunit, to be N-terminally acetylated in NatB mutant yeast. We retargeted Der1 to another acetyltransferase to show that it is the only ERAD factor requiring N-terminal acetylation. Preventing Der1 acetylation stimulates its proteolysis via the Hrd1 pathway, at least partially accounting for the ERAD defect observed in the absence of NatB. These results reveal an important role for N-terminal acetylation in controlling Hrd1 ligase activity toward a specific class of ERAD substrates.

scholarly journals PtdIns3P controls mTORC1 signaling through lysosomal positioning

2017 ◽  
Vol 216 (12) ◽  
pp. 4217-4233 ◽  
Author(s):  
Zhi Hong ◽  
Nina Marie Pedersen ◽  
Ling Wang ◽  
Maria Lyngaas Torgersen ◽  
Harald Stenmark ◽  
...  
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Amino Acid ◽  
Cell Periphery ◽  
Lipid Kinase ◽  
Mechanistic Target Of Rapamycin ◽  
Mtorc1 Signaling ◽  
Transcription Factor Eb ◽  
Mtorc1 Activation

The mechanistic target of rapamycin complex 1 (mTORC1) is a protein kinase complex that localizes to lysosomes to up-regulate anabolic processes and down-regulate autophagy. Although mTORC1 is known to be activated by lysosome positioning and by amino acid–stimulated production of phosphatidylinositol 3-phosphate (PtdIns3P) by the lipid kinase VPS34/PIK3C3, the mechanisms have been elusive. Here we present results that connect these seemingly unrelated pathways for mTORC1 activation. Amino acids stimulate recruitment of the PtdIns3P-binding protein FYCO1 to lysosomes and promote contacts between FYCO1 lysosomes and endoplasmic reticulum that contain the PtdIns3P effector Protrudin. Upon overexpression of Protrudin and FYCO1, mTORC1–positive lysosomes translocate to the cell periphery, thereby facilitating mTORC1 activation. This requires the ability of Protrudin to bind PtdIns3P. Conversely, upon VPS34 inhibition, or depletion of Protrudin or FYCO1, mTORC1-positive lysosomes cluster perinuclearly, accompanied by reduced mTORC1 activity under nutrient-rich conditions. Consequently, the transcription factor EB enters the nucleus, and autophagy is up-regulated. We conclude that PtdIns3P-dependent lysosome translocation to the cell periphery promotes mTORC1 activation.

Identification of topological determinants in the N-terminal domain of transcription factor Nrf1 that control its orientation in the endoplasmic reticulum membrane

2010 ◽  
Vol 430 (3) ◽  
pp. 497-510 ◽  
Author(s):  
Yiguo Zhang ◽  
John D. Hayes
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Signal Peptide ◽  
Leucine Zipper ◽  
Endoplasmic Reticulum Membrane ◽  
Related Factor ◽  
Terminal Domain ◽  
C Terminus ◽  
Er Membrane

Nrf1 [NF-E2 (nuclear factor-erythroid 2)-related factor 1] is a CNC (cap'n'collar) bZIP (basic-region leucine zipper) transcription factor that is tethered to ER (endoplasmic reticulum) and nuclear envelope membranes through its N-terminal signal peptide (residues 1–30). Besides the signal peptide, amino acids 31–90 of Nrf1 also negatively regulate the CNC-bZIP factor. In the present study we have tested the hypothesis that amino acids 31–90 of Nrf1, and the overlapping NHB2 (N-terminal homology box 2; residues 82–106), inhibit Nrf1 because they control its topology within membranes. This region contains three amphipathic α-helical regions comprising amino acids 31–50 [called the SAS (signal peptide-associated sequence)], 55–82 [called the CRACs (cholesterol-recognition amino acid consensus sequences)] and 89–106 (part of NHB2). We present experimental data showing that the signal peptide of Nrf1 contains a TM1 (transmembrane 1) region (residues 7–24) that is orientated across the ER membrane in an Ncyt/Clum fashion with its N-terminus facing the cytoplasm and its C-terminus positioned in the lumen of the ER. Once Nrf1 is anchored to the ER membrane through TM1, the remaining portion of the N-terminal domain (NTD, residues 1–124) is transiently translocated into the ER lumen. Thereafter, Nrf1 adopts a topology in which the SAS is inserted into the membrane, the CRACs are probably repartitioned to the cytoplasmic side of the ER membrane, and NHB2 may serve as an anchor switch, either lying on the luminal surface of the ER or traversing the membrane with an Ncyt/Clum orientation. Thus Nrf1 can adopt several topologies within membranes that are determined by its NTD.

scholarly journals Primary structure requirements for correct sorting of the yeast mitochondrial protein ADH III to the yeast mitochondrial matrix space.

1987 ◽  
Vol 7 (1) ◽  
pp. 294-304 ◽  
Author(s):  
D Pilgrim ◽  
E T Young
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Proteolytic Processing ◽  
Mitochondrial Matrix ◽  
Wild Type ◽  
Mature Form ◽  
Amino Terminal ◽  
The Matrix

Alcohol dehydrogenase isoenzyme III (ADH III) in Saccharomyces cerevisiae, the product of the ADH3 gene, is located in the mitochondrial matrix. The ADH III protein was synthesized as a larger precursor in vitro when the gene was transcribed with the SP6 promoter and translated with a reticulocyte lysate. A precursor of the same size was detected when radioactively pulse-labeled proteins were immunoprecipitated with anti-ADH antibody. This precursor was rapidly processed to the mature form in vivo with a half-time of less than 3 min. The processing was blocked if the mitochondria were uncoupled with carbonyl cyanide m-chlorophenylhydrazone. Mutant enzymes in which only the amino-terminal 14 or 16 amino acids of the presequence were retained were correctly targeted and imported into the matrix. A mutant enzyme that was missing the amino-terminal 17 amino acids of the presequence produced an active enzyme, but the majority of the enzyme activity remained in the cytoplasmic compartment on cellular fractionation. Random amino acid changes were produced in the wild-type presequence by bisulfite mutagenesis of the ADH3 gene. The resulting ADH III protein was targeted to the mitochondria and imported into the matrix in all of the mutants tested, as judged by enzyme activity. Mutants containing amino acid changes in the carboxyl-proximal half of the ADH3 presequence were imported and processed to the mature form at a slower rate than the wild type, as judged by pulse-chase studies in vivo. The unprocessed precursor appeared to be unstable in vivo. It was concluded that only a small portion of the presequence contains the necessary information for correct targeting and import. Furthermore, the information for correct proteolytic processing of the presequence appears to be distinct from the targeting information and may involve secondary structure information in the presequence.

Acquisition of NFKB1-selective DNA binding by substitution of four amino acid residues from NFKB1 into RelA

1993 ◽  
Vol 13 (7) ◽  
pp. 3850-3859
Author(s):  
T A Coleman ◽  
C Kunsch ◽  
M Maher ◽  
S M Ruben ◽  
C A Rosen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dna Binding ◽  
Fusion Protein ◽  
Binding Specificity ◽  
Single Amino Acid ◽  
Nf Kappa B ◽  
Dna Binding Specificity ◽  
Dna Motif ◽  
Single Amino Acid Change

The subunits of NF-kappa B, NFKB1 (formerly p50) and RelA (formerly p65), belong to a growing family of transcription factors that share extensive similarity to the c-rel proto-oncogene product. The homology extends over a highly conserved stretch of approximately 300 amino acids termed the Rel homology domain (RHD). This region has been shown to be involved in both multimerization (homo- and heterodimerization) and DNA binding. It is now generally accepted that homodimers of either subunit are capable of binding DNA that contains a kappa B site originally identified in the immunoglobulin enhancer. Recent studies have demonstrated that the individual subunits of the NF-kappa B transcription factor complex can be distinguished by their ability to bind distinct DNA sequence motifs. By using NFKB1 and RelA subunit fusion proteins, different regions within the RHD were found to confer DNA-binding and multimerization functions. A fusion protein that contains 34 N-terminal amino acids of NFKB1 and 264 amino acids of RelA displayed preferential binding to an NFKB1-selective DNA motif while dimerizing with the characteristics of RelA. Within the NFKB1 portion of this fusion protein, a single amino acid change of His to Arg altered the DNA-binding specificity to favor interaction with the RelA-selective DNA motif. Furthermore, substitution of four amino acids from NFKB1 into RelA was able to alter the DNA-binding specificity of the RelA protein to favor interaction with the NFKB1-selective site. Taken together, these findings demonstrate the presence of a distinct subdomain within the RHD involved in conferring the DNA-binding specificity of the Rel family of proteins.

Single amino acid substitution of rat MRP2 results in acquired transport activity for taurocholate

2001 ◽  
Vol 281 (4) ◽  
pp. G1034-G1043 ◽  
Author(s):  
Kousei Ito ◽  
Hiroshi Suzuki ◽  
Yuichi Sugiyama
Keyword(s):  
Amino Acids ◽  
Multidrug Resistance ◽  
Amino Acid ◽  
Membrane Vesicles ◽  
Single Amino Acid ◽  
Sf9 Cells ◽  
Transport Activity ◽  
Wild Type ◽  
Cationic Amino Acids ◽  
The Difference

Multidrug resistance-associated protein 3 (MRP3), unlike other MRPs, transports taurocholate (TC). The difference in TC transport activity between rat MRP2 and MRP3 was studied, focusing on the cationic amino acids in the transmembrane domains. For analysis, transport into membrane vesicles from Sf9 cells expressing wild-type and mutated MRP2 was examined. Substitution of Arg at position 586 with Leu and Ile and substitution of Arg at position 1096 with Lys, Leu, and Met resulted in the acquisition of TC transport activity, while retaining transport activity for glutathione and glucuronide conjugates. Substitution of Leu at position 1084 of rat MRP3 (which corresponds to Arg-1096 in rat MRP2) with Lys, but not with Val or Met, resulted in the loss of transport activity for TC and glucuronide conjugates. These results suggest that the presence of the cationic charge at Arg-586 and Arg-1096 in rat MRP2 prevents the transport of TC, whereas the presence of neutral amino acids at the corresponding position of rat MRP3 is required for the transport of substrates.

scholarly journals Amino acids whose intracellular levels change most during aging alter chronological lifespan of fission yeast

2020 ◽  
Author(s):  
Charalampos Rallis ◽  
Michael Mülleder ◽  
Graeme Smith ◽  
Yan Zi Au ◽  
Markus Ralser ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fission Yeast ◽  
Yeast Cells ◽  
Total Amino Acid ◽  
Wild Type ◽  
Chronological Lifespan ◽  
Biomarkers Of Aging ◽  
Concentration Changes ◽  
Amino Acid Levels

AbstractAmino acid deprivation or supplementation can affect cellular and organismal lifespan, but we know little about the role of concentration changes in free, intracellular amino acids during aging. Here, we determine free amino-acid levels during chronological aging of non-dividing fission yeast cells. We compare wild-type with long-lived mutant cells that lack the Pka1 protein of the protein kinase A signalling pathway. In wild-type cells, total amino-acid levels decrease during aging, but much less so in pka1 mutants. Two amino acids strongly change as a function of age: glutamine decreases, especially in wild-type cells, while aspartate increases, especially in pka1 mutants. Supplementation of glutamine is sufficient to extend the chronological lifespan of wild-type but not of pka1Δ cells. Supplementation of aspartate, on the other hand, shortens the lifespan of pka1Δ but not of wild-type cells. Our results raise the possibility that certain amino acids are biomarkers of aging, and their concentrations during aging can promote or limit cellular lifespan.

scholarly journals Sequence Analysis and Expression of the Attachment and Fusion Proteins of Canine Distemper Virus Wild-Type Strain A75/17

1999 ◽  
Vol 73 (3) ◽  
pp. 2263-2269 ◽  
Author(s):  
Pascal Cherpillod ◽  
Karin Beck ◽  
Andreas Zurbriggen ◽  
Riccardo Wittek
Keyword(s):  
Amino Acid ◽  
Fusion Protein ◽  
Translation Initiation ◽  
Fusion Proteins ◽  
Canine Distemper Virus ◽  
Protein A ◽  
Biological Properties ◽  
Canine Distemper ◽  
Wild Type ◽  
Attachment Protein

ABSTRACT The biological properties of wild-type A75/17 and cell culture-adapted Onderstepoort canine distemper virus differ markedly. To learn more about the molecular basis for these differences, we have isolated and sequenced the protein-coding regions of the attachment and fusion proteins of wild-type canine distemper virus strain A75/17. In the attachment protein, a total of 57 amino acid differences were observed between the Onderstepoort strain and strain A75/17, and these were distributed evenly over the entire protein. Interestingly, the attachment protein of strain A75/17 contained an extension of three amino acids at the C terminus. Expression studies showed that the attachment protein of strain A75/17 had a higher apparent molecular mass than the attachment protein of the Onderstepoort strain, in both the presence and absence of tunicamycin. In the fusion protein, 60 amino acid differences were observed between the two strains, of which 44 were clustered in the much smaller F2 portion of the molecule. Significantly, the AUG that has been proposed as a translation initiation codon in the Onderstepoort strain is an AUA codon in strain A75/17. Detailed mutation analyses showed that both the first and second AUGs of strain A75/17 are the major translation initiation sites of the fusion protein. Similar analyses demonstrated that, also in the Onderstepoort strain, the first two AUGs are the translation initiation codons which contribute most to the generation of precursor molecules yielding the mature form of the fusion protein.

scholarly journals Mutational Analysis of the Hydrophobic Tail of the Human Immunodeficiency Virus Type 1 p6Gag Protein Produces a Mutant That Fails To Package Its Envelope Protein

1999 ◽  
Vol 73 (1) ◽  
pp. 19-28 ◽  
Author(s):  
David E. Ott ◽  
Elena N. Chertova ◽  
Laura K. Busch ◽  
Lori V. Coren ◽  
Tracy D. Gagliardi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hydrophobic Tail ◽  
Carboxyl Terminal ◽  
Hiv 1

ABSTRACT The p6Gag protein of human immunodeficiency virus type 1 (HIV-1) is produced as the carboxyl-terminal sequence within the Gag polyprotein. The amino acid composition of this protein is high in hydrophilic and polar residues except for a patch of relatively hydrophobic amino acids found in the carboxyl-terminal 16 amino acids. Internal cleavage of p6Gag between Y36 and P37, apparently by the HIV-1 protease, removes this hydrophobic tail region from approximately 30% of the mature p6Gag proteins in HIV-1MN. To investigate the importance of this cleavage and the hydrophobic nature of this portion of p6Gag, site-directed mutations were made at the minor protease cleavage site and within the hydrophobic tail. The results showed that all of the single-amino-acid-replacement mutants exhibited either reduced or undetectable cleavage at the site yet almost all were nearly as infectious as wild-type virus, demonstrating that processing at this site is not important for viral replication. However, one exception, Y36F, was 300-fold as infectious the wild type. In contrast to the single-substitution mutants, a virus with two substitutions in this region of p6Gag, Y36S-L41P, could not infect susceptible cells. Protein analysis showed that while the processing of the Gag precursor was normal, the double mutant did not incorporate Env into virus particles. This mutant could be complemented with surface glycoproteins from vesicular stomatitis virus and murine leukemia virus, showing that the inability to incorporate Env was the lethal defect for the Y36S-L41P virus. However, this mutant was not rescued by an HIV-1 Env with a truncated gp41TM cytoplasmic domain, showing that it is phenotypically different from the previously described MA mutants that do not incorporate their full-length Env proteins. Cotransfection experiments with Y36S-L41P and wild-type proviral DNAs revealed that the mutant Gag dominantly blocked the incorporation of Env by wild-type Gag. These results show that the Y36S-L41P p6Gag mutation dramatically blocks the incorporation of HIV-1 Env, presumably acting late in assembly and early during budding.

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