scholarly journals Comparative characterization of rat deoxyribonuclease 1 (Dnase1) and murine deoxyribonuclease 1-like 3 (Dnase1l3)

2005 ◽  
Vol 389 (2) ◽  
pp. 355-364 ◽  
Author(s):  
Markus Napirei ◽  
Swantje Wulf ◽  
Dirk Eulitz ◽  
Hans Georg Mannherz ◽  
Thomas Kloeckl
Keyword(s):  
Fusion Proteins ◽  
Secretory Pathway ◽  
Nuclear Dna ◽  
Fluorescent Protein ◽  
Recombinant Expression ◽  
Biochemical Properties ◽  
Amino Acid Sequences ◽  
Dnase Γ ◽  
3T3 Fibroblasts ◽  
Green Fluorescent

Deoxyribonuclease 1 (DNASE1, DNase I) and deoxyribonuclease 1-like 3 (DNASE1L3, DNase γ, DNase Y, LS-DNase) are members of a DNASE1 protein family that is defined by similar biochemical properties such as Ca2+/Mg2+-dependency and an optimal pH of about 7.0 as well as by a high similarity in their nucleic acid and amino acid sequences. In the present study we describe the recombinant expression of rat Dnase1 and murine Dnase1l3 as fusion proteins tagged by their C-terminus to green fluorescent protein in NIH-3T3 fibroblasts and bovine lens epithelial cells. Both enzymes were translocated into the rough endoplasmic reticulum, transported along the entire secretory pathway and finally secreted into the cell culture medium. No nuclear occurrence of the nucleases was detectable. However, deletion of the N-terminal signal peptide of both nucleases resulted in a cytoplasmic and nuclear distribution of both fusion proteins. Dnase1 preferentially hydrolysed ‘naked’ plasmid DNA, whereas Dnase1l3 cleaved nuclear DNA with high activity. Dnase1l3 was able to cleave chromatin in an internucleosomal manner without proteolytic help. By contrast, Dnase1 was only able to achieve this cleavage pattern in the presence of proteases that hydrolysed chromatin-bound proteins. Detailed analysis of murine sera derived from Dnase1 knockout mice revealed that serum contains, besides the major serum nuclease Dnase1, an additional Dnase1l3-like nucleolytic activity, which, in co-operation with Dnase1, might help to suppress anti-DNA autoimmunity by degrading nuclear chromatin released from dying cells.

Factor VIII-eGFP fusion proteins with preserved functional activity for the analysis of the early secretory pathway of factor VIII

2009 ◽  
Vol 102 (11) ◽  
pp. 925-935 ◽  
Author(s):  
Stefan Heinz ◽  
Jörg Schüttrumpf ◽  
Jeremy Simpson ◽  
Rainer Pepperkok ◽  
Gerry Nicolaes ◽  
...  
Keyword(s):  
Factor Viii ◽  
Fusion Proteins ◽  
Secretory Pathway ◽  
Fluorescent Protein ◽  
Recombinant Expression ◽  
Early Secretory Pathway ◽  
C Terminus ◽  
Living Organisms ◽  
Green Fluorescent

SummaryConsidering the difficulty in detecting factor (F)VIII in vivo, fluorescently labelled FVIII protein provides a tool to analyse the intracellular localisation, bio distribution, and pharmacokinetics of the protein in living organisms. Here, we report the use of FVIII full length and B-domain deleted proteins, fused to enhanced green fluorescent protein (eGFP) at the C-terminus of the coagulation protein via a nine amino acid spanning linker. Comparison of the FVIII-eGFP fusion proteins to their unlabelled counterparts showed no impairment with respect to recombinant expression levels, intracellular processing, specific coagulant activity and decay at physiological temperature. Confocal live cell imaging demonstrated ER-Golgi-transport of B-domain deleted FVIII-eGFP in vesicular tubular carriers. Using temperature blocks and release experiments, imaging of FVIII-eGFP fusion proteins enabled for the first time the visualisation of the early secretory pathway of B-domain deleted FVIII in living cells and in particular highlighted the apparent deficit of active transport carriers, an observation consistent with the low rates of FVIII secretion seen in recombinant expression systems.

scholarly journals Rem2, a new member of the Rem/Rad/Gem/Kir family of Ras-related GTPases

2000 ◽  
Vol 347 (1) ◽  
pp. 223-231 ◽  
Author(s):  
Brian S. FINLIN ◽  
Haipeng SHAO ◽  
Keiko KADONO-OKUDA ◽  
Nan GUO ◽  
Douglas A. ANDRES
Keyword(s):  
Cellular Localization ◽  
Biochemical Characterization ◽  
Fluorescent Protein ◽  
Dissociation Constants ◽  
Intrinsic Rate ◽  
Biochemical Properties ◽  
Cell Physiology ◽  
Gtp Binding ◽  
C Terminus ◽  
Green Fluorescent

Here we report the molecular cloning and biochemical characterization of Rem2 (for Rem, ad and G-related 2), a novel GTP-binding protein identified on the basis of its homology with the Rem, Rad, Gem and Kir (RGK) family of Ras-related small GTP-binding proteins. Rem2 mRNA was detected in rat brain and kidney, making it the first member of the RGK family to be expressed at relatively high levels in neuronal tissues. Recombinant Rem2 binds GTP saturably and exhibits a low intrinsic rate of GTP hydrolysis. Surprisingly, the guanine nucleotide dissociation constants for both Rem2 and Rem are significantly different than the majority of the Ras-related GTPases, displaying higher dissociation rates for GTP than GDP. Localization studies with green fluorescent protein (GFP)-tagged recombinant protein fusions indicate that Rem2 has a punctate, plasma membrane localization. Deletion of the C-terminal seven amino acid residues that are conserved in all RGK family members did not affect the cellular distribution of the GFP fusion protein, whereas a larger deletion, including much of the polybasic region of the Rem2 C-terminus, resulted in its redistribution to the cytosol. Thus Rem2 is a GTPase of the RGK family with distinctive biochemical properties and possessing a novel cellular localization signal, consistent with its having a unique role in cell physiology.

scholarly journals Bifunctional fusion proteins containing the sequence of the bradykinin homologue maximakinin: activities at the rat bradykinin B2 receptor

2018 ◽  
Vol 96 (5) ◽  
pp. 459-470 ◽  
Author(s):  
Xavier Charest-Morin ◽  
Robert Lodge ◽  
François Marceau
Keyword(s):  
Fusion Proteins ◽  
Enhanced Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Protein Denaturation ◽  
Epifluorescence Microscopy ◽  
Terminal Sequence ◽  
Protein Ligands ◽  
C Terminus ◽  
Bona Fide ◽  
Green Fluorescent

To support bradykinin (BK) B2 receptor (B2R) detection and therapeutic stimulation, we developed and characterized fusion proteins consisting of the BK homolog maximakinin (MK), or variants, positioned at the C-terminus of functional proteins (enhanced green fluorescent protein (EGFP), the peroxidase APEX2, or human serum albumin (HSA)). EGFP-MK loses its reactivity with anti-BK antibodies and molecular mass as it progresses in the endosomal tract of cells expressing rat B2Rs (immunoblots, epifluorescence microscopy). APEX2-(NG)15-MK is a bona fide agonist of the rat, but not of the human B2R (calcium and c-Fos signaling) and is compatible with the cytochemistry reagent TrueBlue (microscopy), a luminol-based reagent, or 3,3′,5,5′-tetramethylbenzidine (luminescence or colourimetric B2R detection, cell well plate format). APEX2-(NG)15-MK is a non-isotopic ligand suitable for drug discovery via binding competition. Affinity-purified secreted forms of HSA fused with peptides possessing the C-terminal MK or BK sequence failed to stimulate the rat B2R in the concentration range of 50–600 nmol/L. However, the non-secreted construction myc-HSA-MK is a B2R agonist, indicating that protein denaturation made the C-terminal sequence available for receptor binding. Fusion protein ligands of the B2R are stable but subjected to slow intracellular inactivation, strong species specificity, and possible steric hindrance between the receptor and large proteins.

Transport Through the Secretory Pathway of VSVG Tagged With Green Fluorescent Protein: Role of Tubulovesicular Carriers and Microtubules

1997 ◽  
Vol 3 (S2) ◽  
pp. 139-140
Author(s):  
John Presley ◽  
Koret Hirschberg ◽  
Nelson Cole
Keyword(s):  
Green Fluorescent Protein ◽  
Membrane Transport ◽  
G Protein ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Fluorescent Protein ◽  
Dynamic Properties ◽  
Living Cells ◽  
Morphological Properties ◽  
Green Fluorescent

The ts045 mutant of VSV G protein has been used in numerous studies to identify biochemical and morphological properties of membrane transport, due to its reversible misfolding and retention in the ER at 40°C and ability to traffic out of the ER and into the Golgi complex upon temperature reduction to 32oC. The dynamic properties of membrane transport intermediates of the secretory pathway, including their lifetime and fate within cells, have not until now been explored due to the inability to follow transport in single living cells. Here, we attached green fluorescent protein to the cytoplasmic tail of VSV G protein in order to visualize ER-to-Golgi and Golgi-to-plasma membrane transport in living cells. VSVG-GFP expressed in Cos cells accumulated in the ER at 40°C and translocated to the Golgi complex when shifted to 32oC. Translocation of the protein was followed using time-lapse imaging of live cells on a confocal microscope. VSVG-GFP accumulated in tubulovesicular structures scattered throughout the cell upon shift from 40°C to 15°C for three hours.

scholarly journals Chaperone-mediated reflux of secretory proteins to the cytosol during endoplasmic reticulum stress

2019 ◽  
Vol 116 (23) ◽  
pp. 11291-11298 ◽  
Author(s):  
Aeid Igbaria ◽  
Philip I. Merksamer ◽  
Ala Trusina ◽  
Firehiwot Tilahun ◽  
Jeffrey R. Johnson ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Secretory Pathway ◽  
Protein Quality ◽  
Fluorescent Protein ◽  
Control Process ◽  
Secretory Proteins ◽  
Quality Control Process ◽  
Folded Proteins ◽  
Green Fluorescent

Diverse perturbations to endoplasmic reticulum (ER) functions compromise the proper folding and structural maturation of secretory proteins. To study secretory pathway physiology during such “ER stress,” we employed an ER-targeted, redox-responsive, green fluorescent protein—eroGFP—that reports on ambient changes in oxidizing potential. Here we find that diverse ER stress regimes cause properly folded, ER-resident eroGFP (and other ER luminal proteins) to “reflux” back to the reducing environment of the cytosol as intact, folded proteins. By utilizing eroGFP in a comprehensive genetic screen in Saccharomyces cerevisiae, we show that ER protein reflux during ER stress requires specific chaperones and cochaperones residing in both the ER and the cytosol. Chaperone-mediated ER protein reflux does not require E3 ligase activity, and proceeds even more vigorously when these ER-associated degradation (ERAD) factors are crippled, suggesting that reflux may work in parallel with ERAD. In summary, chaperone-mediated ER protein reflux may be a conserved protein quality control process that evolved to maintain secretory pathway homeostasis during ER protein-folding stress.

scholarly journals Functional Analysis of the ATG8 Homologue Aoatg8 and Role of Autophagy in Differentiation and Germination in Aspergillus oryzae

2006 ◽  
Vol 5 (8) ◽  
pp. 1328-1336 ◽  
Author(s):  
Takashi Kikuma ◽  
Mamoru Ohneda ◽  
Manabu Arioka ◽  
Katsuhiko Kitamoto
Keyword(s):  
Aspergillus Oryzae ◽  
Fusion Proteins ◽  
Fluorescent Protein ◽  
Normal Growth ◽  
Nitrogen Sources ◽  
Growth Conditions ◽  
Conidial Germination ◽  
Aerial Hyphae ◽  
Green Fluorescent ◽  
Starvation Conditions

ABSTRACT Autophagy is a well-known degradation system, induced by nutrient starvation, in which cytoplasmic components and organelles are digested via vacuoles/lysosomes. Recently, it was reported that autophagy is involved in the turnover of cellular components, development, differentiation, immune responses, protection against pathogens, and cell death. In this study, we isolated the ATG8 gene homologue Aoatg8 from the filamentous fungus Aspergillus oryzae and visualized autophagy by the expression of DsRed2-AoAtg8 and enhanced green fluorescent protein-AoAtg8 fusion proteins in this fungus. While the fusion proteins were localized in dot structures which are preautophagosomal structure-like structures under normal growth conditions, starvation or rapamycin treatment caused their accumulation in vacuoles. DsRed2 expressed in the cytoplasm was also taken up into vacuoles under starvation conditions or during the differentiation of conidiophores and conidial germination. Deletion mutants of Aoatg8 did not form aerial hyphae and conidia, and DsRed2 was not localized in vacuoles under starvation conditions, indicating that Aoatg8 is essential for autophagy. Furthermore, Aoatg8 conditional mutants showed delayed conidial germination in the absence of nitrogen sources. These results suggest that autophagy functions in both the differentiation of aerial hyphae and in conidial germination in A. oryzae.

Targeting motifs and functional parameters governing the assembly of connexins into gap junctions

2000 ◽  
Vol 349 (1) ◽  
pp. 281-287 ◽  
Author(s):  
Patricia E. M. MARTIN ◽  
James STEGGLES ◽  
Claire WILSON ◽  
Shoeb AHMAD ◽  
W. Howard EVANS
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Gap Junctions ◽  
Gap Junction ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Lucifer Yellow ◽  
Amino Acid Sequences ◽  
Amino Acid Residues ◽  
Green Fluorescent

To study the assembly of gap junctions, connexin-green-fluorescent-protein (Cx-GFP) chimeras were expressed in COS-7 and HeLa cells. Cx26- and Cx32-GFP were targeted to gap junctions where they formed functional channels that transferred Lucifer Yellow. A series of Cx32-GFP chimeras, truncated from the C-terminal cytoplasmic tail, were studied to identify amino acid sequences governing targeting from intracellular assembly sites to the gap junction. Extensive truncation of Cx32 resulted in failure to integrate into membranes. Truncation of Cx32 to residue 207, corresponding to removal of most of the 78 amino acids on the cytoplasmic C-terminal tail, led to arrest in the endoplasmic reticulum and incomplete oligomerization. However, truncation to amino acid 219 did not impair Cx oligomerization and connexon hemichannels were targeted to the plasma membrane. It was concluded that a crucial gap-junction targeting sequence resides between amino acid residues 207 and 219 on the cytoplasmic C-terminal tail of Cx32. Studies of a Cx32E208K mutation identified this as one of the key amino acids dictating targeting to the gap junction, although oligomerization of this site-specific mutation into hexameric hemichannels was relatively unimpaired. The studies show that expression of these Cx-GFP constructs in mammalian cells allowed an analysis of amino acid residues involved in gap-junction assembly.

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