scholarly journals A Developmentally Regulated Chaperone Complex for the Endoplasmic Reticulum of Male Haploid Germ Cells

2007 ◽  
Vol 18 (8) ◽  
pp. 2795-2804 ◽  
Author(s):  
Marcel van Lith ◽  
Anna-Riikka Karala ◽  
Dave Bown ◽  
John A. Gatehouse ◽  
Lloyd W. Ruddock ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Germ Cells ◽  
Specific Protein ◽  
Developmentally Regulated ◽  
C Terminus ◽  
Pancreatic Trypsin Inhibitor ◽  
Disulfide Isomerases ◽  
Chaperone Complex

Glycoprotein folding is mediated by lectin-like chaperones and protein disulfide isomerases (PDIs) in the endoplasmic reticulum. Calnexin and the PDI homologue ERp57 work together to help fold nascent polypeptides with glycans located toward the N-terminus of a protein, whereas PDI and BiP may engage proteins that lack glycans or have sugars toward the C-terminus. In this study, we show that the PDI homologue PDILT is expressed exclusively in postmeiotic male germ cells, in contrast to the ubiquitous expression of many other PDI family members in the testis. PDILT is induced during puberty and represents the first example of a PDI family member under developmental control. We find that PDILT is not active as an oxido-reductase, but interacts with the model peptide Δ-somatostatin and nonnative bovine pancreatic trypsin inhibitor in vitro, indicative of chaperone activity. In vivo, PDILT forms a tissue-specific chaperone complex with the calnexin homologue calmegin. The identification of a redox-inactive chaperone partnership defines a new system of testis-specific protein folding with implications for male fertility.

scholarly journals The C-terminus of cytochrome b5 confers endoplasmic reticulum specificity by preventing spontaneous insertion into membranes

2007 ◽  
Vol 401 (3) ◽  
pp. 701-709 ◽  
Author(s):  
Matthew P. A. Henderson ◽  
Yeen Ting Hwang ◽  
John M. Dyer ◽  
Robert T. Mullen ◽  
David W. Andrews
Keyword(s):  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Lipid Bilayers ◽  
Fusion Proteins ◽  
Molecular Mechanisms ◽  
Cytochrome B5 ◽  
Terminal Sequence ◽  
C Terminus

The molecular mechanisms that determine the correct subcellular localization of proteins targeted to membranes by tail-anchor sequences are poorly defined. Previously, we showed that two isoforms of the tung oil tree [Vernicia (Aleurites) fordii] tail-anchored Cb5 (cytochrome b5) target specifically to ER (endoplasmic reticulum) membranes both in vivo and in vitro [Hwang, Pelitire, Henderson, Andrews, Dyer and Mullen (2004) Plant Cell 16, 3002–3019]. In the present study, we examine the targeting of various tung Cb5 fusion proteins and truncation mutants to purified intracellular membranes in vitro in order to assess the importance of the charged CTS (C-terminal sequence) in targeting to specific membranes. Removal of the CTS from tung Cb5 proteins resulted in efficient binding to both ER and mitochondria. Results from organelle competition, liposome-binding and membrane proteolysis experiments demonstrated that removal of the CTS results in spontaneous insertion of tung Cb5 proteins into lipid bilayers. Our results indicate that the CTSs from plant Cb5 proteins provide ER specificity by preventing spontaneous insertion into incorrect subcellular membranes.

scholarly journals A Proteomic Network Approach across the Kidney Stone Disease Reveals Endoplasmic Reticulum Stress and Crystal-Cell Interaction in the Kidney

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Baoyu Yang ◽  
Xiuli Lu ◽  
Yang Li ◽  
Yuanyuan Li ◽  
Daojun Yu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Kidney Stone ◽  
Protein Modification ◽  
Stone Formation ◽  
Specific Protein ◽  
Cell Interactions ◽  
Crystal Cell

Crystal-cell interactions are a vital step toward kidney stone formation. However, its mechanisms remained unclear. Here, a protein-protein interaction (PPI) network analysis of a kidney stone revealed that the proteins were enriched in a posttranslational protein modification process in the endoplasmic reticulum (ER). The in vitro study showed that the markers of ER stress, including Bip and CHOP, were upregulated, PERK and ATF6 were activated, and XBP-1 mRNA was spliced. An ER stress-specific protein, caspase-12, was activated in the apoptotic cells induced by calcium oxalate monohydrate (COM) crystals. The treatment with tunicamycin, an ER stress inducer, promoted the crystal-cell adhesion assayed by atomic absorption, reduced cell viability assayed by MTT, and downregulated the expression of proteins involved in the crystal formations. The treatment with salubrinal, an ER stress inhibitor, reversed the above effects for both tunicamycin and COM crystals. The aforementioned main observations were supported by in vivo study. These data demonstrated that ER stress was an essentially biological process of crystal-cell interactions. Our findings suggest that blocking ER stress may become a potential approach to preventing a kidney stone.

scholarly journals PRDM9 forms an active trimer mediated by its repetitive zinc finger array

2018 ◽  
Author(s):  
Theresa Schwarz ◽  
Yasmin Striedner ◽  
Karin Haase ◽  
Jasmin Kemptner ◽  
Nicole Zeppezauer ◽  
...  
Keyword(s):  
Strand Break ◽  
Specific Protein ◽  
Binding Studies ◽  
Recombination Hotspots ◽  
C Terminus ◽  
Dna Binding Site ◽  
Vitro Binding ◽  
Meiotic Initiation

PRDM9 has been identified as a meiosis-specific protein that plays a key role in determining the location of meiotic recombination hotspots. Although it is well-established that PRDM9 is a trans-acting factor directing the double strand break machinery necessary for recombination to its DNA binding site, the details of PRDM9 binding and complex formation are not well known. It has been suggested in several instances that PRDM9 acts as a multimer in vivo; however, there is little understanding about the protein stoichiometry or the components inducing PRDM9 multimerization. In this work, we used in vitro binding studies and mass spectrometry to characterize the size of the PRDM9 multimer within the active DNA-protein complex of two different murine PRDM9 alleles, PRDM9Cst and PRDM9Dom2. For this purpose, we developed a strategy to infer the molecular weight of the PRDM9-DNA complex from native gel electrophoresis based on gel shift assays (EMSAs). Our results show that PRDM9 binds as a trimer with the DNA. This multimerization is catalysed by the long ZnF array (ZnF) at the C-terminus of the protein and 11, 10, 7 or 5 ZnFs are already sufficient to form a functional trimer. Finally, we also show that only one ZnF-array within the PRDM9 trimer actively binds to the DNA, while the remaining two ZnF-arrays likely maintain the multimer by ZnF-ZnF interactions. Our results have important implications in terms of PRDM9 dosage, which determines the number of active hotspots in meiotic cells, and contribute to elucidate the molecular interactions of PRDM9 with other components of the meiotic initiation machinery.

scholarly journals Targeting of a Tail-anchored Protein to Endoplasmic Reticulum and Mitochondrial Outer Membrane by Independent but Competing Pathways

2001 ◽  
Vol 12 (8) ◽  
pp. 2482-2496 ◽  
Author(s):  
Nica Borgese ◽  
Ilaria Gazzoni ◽  
Massimo Barberi ◽  
Sara Colombo ◽  
Emanuela Pedrazzini
Keyword(s):  
Endoplasmic Reticulum ◽  
Outer Membrane ◽  
Fluorescent Protein ◽  
Transmembrane Domain ◽  
Mitochondrial Outer Membrane ◽  
C Terminus ◽  
Green Fluorescent ◽  
Ta Proteins

Many mitochondrial outer membrane (MOM) proteins have a transmembrane domain near the C terminus and an N-terminal cytosolic moiety. It is not clear how these tail-anchored (TA) proteins posttranslationally select their target, but C-terminal charged residues play an important role. To investigate how discrimination between MOM and endoplasmic reticulum (ER) occurs, we used mammalian cytochrome b 5, a TA protein existing in two, MOM or ER localized, versions. Substitution of the seven C-terminal residues of the ER isoform or of green fluorescent protein reporter constructs with one or two arginines resulted in MOM-targeted proteins, whereas a single C-terminal threonine caused promiscuous localization. To investigate whether targeting to MOM occurs from the cytosol or after transit through the ER, we tagged a MOM-directed construct with a C-terminal N-glycosylation sequence. Although in vitro this construct was efficiently glycosylated by microsomes, the protein expressed in vivo localized almost exclusively to MOM, and was nearly completely unglycosylated. The small fraction of glycosylated protein was in the ER and was not a precursor to the unglycosylated form. Thus, targeting occurs directly from the cytosol. Moreover, ER and MOM compete for the same polypeptide, explaining the dual localization of some TA proteins.

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

scholarly journals A Peptide Found in Human Serum, Derived from the C-Terminus of Albumin, Shows Antifungal Activity In Vitro and In Vivo

2020 ◽  
Vol 8 (10) ◽  
pp. 1627
Author(s):  
Tecla Ciociola ◽  
Pier Paolo Zanello ◽  
Tiziana D’Adda ◽  
Serena Galati ◽  
Stefania Conti ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Human Serum ◽  
Fungicidal Activity ◽  
Galleria Mellonella ◽  
Serum Proteins ◽  
Morphological Alterations ◽  
C Terminus ◽  
Different Sources

The growing problem of antimicrobial resistance highlights the need for alternative strategies to combat infections. From this perspective, there is a considerable interest in natural molecules obtained from different sources, which are shown to be active against microorganisms, either alone or in association with conventional drugs. In this paper, peptides with the same sequence of fragments, found in human serum, derived from physiological proteins, were evaluated for their antifungal activity. A 13-residue peptide, representing the 597–609 fragment within the albumin C-terminus, was proved to exert a fungicidal activity in vitro against pathogenic yeasts and a therapeutic effect in vivo in the experimental model of candidal infection in Galleria mellonella. Studies by confocal microscopy and transmission and scanning electron microscopy demonstrated that the peptide penetrates and accumulates in Candida albicans cells, causing gross morphological alterations in cellular structure. These findings add albumin to the group of proteins, which already includes hemoglobin and antibodies, that could give rise to cryptic antimicrobial fragments, and could suggest their role in anti-infective homeostasis. The study of bioactive fragments from serum proteins could open interesting perspectives for the development of new antimicrobial molecules derived by natural sources.

scholarly journals C-Terminal Deletions Can Suppress Temperature-Sensitive Mutations and Change Dominance in the Phage Mu Repressor

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 661-672 ◽  
Author(s):  
Jodi L Vogel ◽  
Vincent Geuskens ◽  
Lucie Desmet ◽  
N Patrick Higgins ◽  
Ariane Toussaint
Keyword(s):  
Binding Activity ◽  
Temperature Sensitive ◽  
Dna Binding Activity ◽  
Heat Stable ◽  
C Terminus ◽  
Acid Domain ◽  
Mutant Forms ◽  
Amino Acid Domain

Abstract Mutations in an N-terminal 70-amino acid domain of bacteriophage Mu's repressor cause temperature-sensitive DNA-binding activity. Surprisingly, amber mutations can conditionally correct the heat-sensitive defect in three mutant forms of the repressor gene, cts25 (D43-G), cts62 (R47-Q and cts71 (M28-I), and in the appropriate bacterial host produce a heat-stable Sts phenotype (for survival of temperature shifts). Sts repressor mutants are heat sensitive when in supE or supF hosts and heat resistant when in Sup° hosts. Mutants with an Sts phenotype have amber mutations at one of three codons, Q179, Q187, or Q190. The Sts phenotype relates to the repressor size: in Sup° hosts sts repressors are shorter by seven, 10, or 18 amino acids compared to repressors in supE or supF hosts. The truncated form of the sts62-1 repressor, which lacks 18 residues (Q179–V196), binds Mu operator DNA more stably at 42° in vitro compared to its full-length counterpart (cts62 repressor). In addition to influencing temperature sensitivity, the C-terminus appears to control the susceptibility to in vivo Clp proteolysis by influencing the multimeric structure of repressor.

scholarly journals TMOD-24. GENERATION AND CHARACTERIZATION OF A NOVEL TRANSGENIC IDO REPORTER MOUSE FOR IDO POSTTRANSLATIONAL MODIFICATION ANALYSIS IN SITU

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii233-ii233
Author(s):  
April Bell ◽  
Lijie Zhai ◽  
Erik Ladomersky ◽  
Kristen Lauing ◽  
Lakshmi Bollu ◽  
...  
Keyword(s):  
Mouse Model ◽  
Tumor Cell ◽  
Central Nervous System Tumor ◽  
Post Translational Modifications ◽  
Reporter Mouse ◽  
C Terminus ◽  
Human Gbm

Abstract Glioblastoma (GBM) is the most common and aggressive primary central nervous system tumor in adults with a median survival of 14.6 months. GBM is a potently immunosuppressive cancer due in-part to the prolific expression of immunosuppressive indoleamine 2,3 dioxygenase 1 (IDO). Tumor cell IDO facilitates the intratumoral accumulation of regulatory T cells (Tregs; CD4+CD25+FoxP3+). Although immunosuppressive IDO activity is canonically characterized by the conversion of tryptophan into kynurenine, we have utilized transgenic and syngeneic mouse models and mutant glioma lines to demonstrate that tumor cell IDO increases Treg accumulation independent of tryptophan metabolism. Here, we address the gap in our understanding of IDO signaling activity in vivo. Subcutaneously-engrafted human GBM expressing human IDO-GFP cDNA was isolated from immunodeficient humanized NSG-SGM3 mice. The tumor was immunoprecipitated for the GFP tag using GFP-TRAP followed by mass spectrometry which revealed a novel methylation site on a lysine residue at amino acid 373 in the IDO C-terminus region. Western blot analysis of IDO protein also revealed the presence of tyrosine phosphorylation. Additionally, we recently created a new transgenic IDO reporter mouse model whereby endogenous IDO is fused to GFP via a T2A linker (IDO→GFP). This model allows for the isolation of IDO+ cells in real-time and without causing cell death, thereby creating the opportunity for downstream molecular analysis of in situ-isolated GFP+ cells. Collectively, our work suggests that IDO non-enzyme activity may involve the post-translational modifications we recently identified. As IDO activity may differ between in vitro and in vivo modeling systems, we will use the new IDO→GFP reporter mouse model for an improved mechanistic understanding of how immunosuppressive IDO facilitates Treg accumulation in vivo.

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