scholarly journals Point mutations in bovine opsin can be classified in four groups with respect to their effect on the biosynthetic pathway of opsin

1996 ◽  
Vol 320 (3) ◽  
pp. 807-815 ◽  
Author(s):  
Godelieve L. J. DeCALUWÉ ◽  
Willem J. DeGRIP
Keyword(s):  
Structural Changes ◽  
Expression System ◽  
Point Mutations ◽  
Recombinant Baculovirus ◽  
Baculovirus Expression System ◽  
Heterogeneous Distribution ◽  
Functional Consequences ◽  
Transfer Signal ◽  
Translational Process

Expression in vitro with the recombinant baculovirus expression system showed correct biosynthesis and post-translational processing of ‘wild-type’ bovine opsin with regard to translocation, glycosylation, palmitoylation and targeting. However, several of these processes were severely affected by point mutations. From the overall results of 16 mutants reported here, four groups were distinguished. One group significantly affected neither biosynthesis nor folding of opsin (D83N, P291A, A299C-V300A-P303G). A second group produced a truncated protein (R69H, Y301F), suggesting that these positions are essential for a correct translational process. A third group affected membrane translocation as well as glycosylation, which can be interpreted as interference with the function of a transfer signal. Substitutions at positions Glu-113, Glu-122, Glu-134, Arg-135 and Lys-248 belong to this category. A fourth group induced structural changes in the protein that led to heterogeneous distribution in the plasma membrane (E113Q/D, W265F, Y268S). Taking any functional consequences of these mutations into consideration, it seems that point mutations can have mosaic effects and therefore should be examined at several levels (folding, targeting, functional parameters).

scholarly journals Large-scale production and purification of functional recombinant bovine rhodopsin with the use of the baculovirus expression system

1999 ◽  
Vol 342 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Corné H. W. KLAASSEN ◽  
Petra H. M. BOVEE-GEURTS ◽  
Godelieve L. J. DECALUWÉ ◽  
Willem J. DEGRIP
Keyword(s):  
Membrane Proteins ◽  
Large Scale ◽  
Structural Changes ◽  
Expression System ◽  
Recombinant Baculovirus ◽  
Baculovirus Expression System ◽  
Scale Production ◽  
Protein Activation ◽  
Bovine Rhodopsin ◽  
Lipid Environment

Here we describe a generic procedure for the expression and purification of milligram quantities of functional recombinant eukaryotic integral membrane proteins, exemplified by hexahistidine-tagged bovine rhodopsin. These quantities were obtained with the recombinant baculovirus/Sf9 insect cell-based expression system in large-scale bioreactor cultures with the use of a serum-free and protein-free growth medium. After optimization procedures, expression levels up to 4 mg/l were established. The recombinant rhodopsin could be purified with high overall yield by using immobilized-metal-affinity chromatography on Ni2+-agarose. After reconstitution into a native lipid environment, the purified protein was functionally indistinguishable from native rhodopsin with regard to the following parameters: spectral absorbance band, structural changes after photoactivation, and G-protein activation. The procedures developed can be adapted to other membrane proteins. The ability to produce and purify tens of milligrams of functional recombinant eukaryotic membrane protein meets the ever-increasing demand of material necessary to perform detailed biochemical and structural biophysical studies that are essential in unravelling their working mechanism at a molecular level.

Biochemical Chgaracterization of Recombinant Baculovirus 373 K/E p53 Protein

2018 ◽  
Vol 9 (03) ◽  
pp. 20204-20223
Author(s):  
Maghsoudi, Hossein ◽  
U Pati
Keyword(s):  
Dna Binding ◽  
P53 Protein ◽  
Expression System ◽  
Gel Filtration ◽  
Recombinant Baculovirus ◽  
Baculovirus Expression System ◽  
Cross Linking ◽  
Mobility Shift ◽  
Dna Complexes ◽  
P53 Antibodies

In this study, we expressed and purified the recombinant baculovirus 373 K/E p53 protein in a baculovirus expression system to characterize this mutant and compare it with wild type p53. Gel- filtration chromatography and chemical cross-linking experiments indicated that purified recombinant baculovirus 373 K/E p53 protein assembles into multimeric forms ranging from tetramers to polymers. Gel-mobility shift assays and protein-DNA cross-linking studies demonstrated that the recombinant protein binds, to a consensus DNA target as a dimer but that additional p53 mutant molecules may then associate with the preformed p53-dimer-DNA complexes to form a larger p53_DNA complexes. These observations suggest that the p53 mutant tetramers and polymers that forms the minimal p53 mutant complex in solution dissociated upon DNA binding to form p53 mutant dimmer DNA complexes. The DNA binding activity of this mutant was then investigated using electrophoretic mobility shift assays as well as supershift assay with anti-p53 antibodies. Binding of the anti-p53 antibody PAb421to the oligomerization promoting domain on p53 stimulated the sequential formation of both the p53_dimer DNA and larger p53-DNA complexes

scholarly journals Glutamine synthetase as a central element in hepatic glutamine and ammonia metabolism: novel aspects

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Benedikt Frieg ◽  
Boris Görg ◽  
Holger Gohlke ◽  
Dieter Häussinger
Keyword(s):  
Glutamine Synthetase ◽  
Protein Function ◽  
Nitrosative Stress ◽  
Point Mutations ◽  
Central Element ◽  
Ph Sensitive ◽  
Tyrosine Nitration ◽  
Ammonia Metabolism ◽  
Functional Consequences

Abstract Glutamine synthetase (GS) in the liver is expressed in a small perivenous, highly specialized hepatocyte population and is essential for the maintenance of low, non-toxic ammonia levels in the organism. However, GS activity can be impaired by tyrosine nitration of the enzyme in response to oxidative/nitrosative stress in a pH-sensitive way. The underlying molecular mechanism as investigated by combined molecular simulations and in vitro experiments indicates that tyrosine nitration can lead to a fully reversible and pH-sensitive regulation of protein function. This approach was also used to understand the functional consequences of several recently described point mutations of human GS with clinical relevance and to suggest an approach to restore impaired GS activity.

scholarly journals CD28-independent, TRAF2-dependent Costimulation of Resting T Cells by 4-1BB Ligand

1998 ◽  
Vol 187 (11) ◽  
pp. 1849-1862 ◽  
Author(s):  
Katina Saoulli ◽  
Soo Young Lee ◽  
Jennifer L. Cannons ◽  
Wen Chen Yeh ◽  
Angela Santana ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Expression System ◽  
Baculovirus Expression System ◽  
Dominant Negative ◽  
Soluble Form ◽  
Tnf Receptor

4-1BB ligand (4-1BBL) is a member of the tumor necrosis factor (TNF) family expressed on activated antigen-presenting cells. Its receptor, 4-1BB, is a member of the TNF receptor family expressed on activated CD4 and CD8 T cells. We have produced a soluble form of 4-1BBL using the baculovirus expression system. When coimmobilized on plastic with anti-CD3, soluble 4-1BBL induces interleukin (IL)-2 production by resting CD28+ or CD28− T cells, indicating that 4-1BBL can function independently of other cell surface molecules, including CD28, in costimulation of resting T cell activation. At low concentrations of anti-CD3, 4-1BBL is inferior to anti-CD28 in T cell activation. However, when 4-1BB ligand is provided together with strong TCR signals, then 4-1BBL and anti-CD28 are equally potent in stimulation of IL-2 production by resting T cells. We find that TNF receptor–associated factor (TRAF)1 or TRAF2 associate with a glutathione S-transferase–4-1BB cytoplasmic domain fusion protein in vitro. In T cells, we find that association of TRAF1 and TRAF2 with 4-1BB requires 4-1BB cross-linking. In support of a functional role for TRAF2 in 4-1BB signaling, we find that resting T cells isolated from TRAF2-deficient mice or from mice expressing a dominant negative form of TRAF2 fail to augment IL-2 production in response to soluble 4-1BBL. Thus 4-1BB, via the TRAF2 molecule, can provide CD28-independent costimulatory signals to resting T cells.

scholarly journals Characterisation of three novel CYP11B1 mutations in classic and non-classic 11β-hydroxylase deficiency

2014 ◽  
Vol 170 (5) ◽  
pp. 697-706 ◽  
Author(s):  
Seher Polat ◽  
Alexandra Kulle ◽  
Züleyha Karaca ◽  
Ilker Akkurt ◽  
Selim Kurtoglu ◽  
...  
Keyword(s):  
Expression System ◽  
Three Dimensional ◽  
Gene Mutations ◽  
Dimensional Structure ◽  
Hydroxylase Deficiency ◽  
Mutant Proteins ◽  
Maximum Reaction ◽  
Functional Consequences ◽  
21 Hydroxylase Deficiency

BackgroundCongenital adrenal hyperplasia (CAH) is one of the most common autosomal recessive inherited endocrine diseases. Steroid 11β-hydroxylase (P450c11) deficiency (11OHD) is the second most common form of CAH.AimThe aim of the study was to study the functional consequences of three novelCYP11B1gene mutations (p.His125Thrfs*8, p.Leu463_Leu464dup and p.Ser150Leu) detected in patients suffering from 11OHD and to correlate this data with the clinical phenotype.MethodsFunctional analyses were done by using a HEK293 cellin vitroexpression system comparing WT with mutant P450c11 activity. Mutant proteins were examinedin silicoto study their effect on the three-dimensional structure of the protein.ResultsTwo mutations (p.His125Thrfs*8 and p.Leu463_Leu464dup) detected in patients with classic 11OHD showed a complete loss of P450c11 activity. The mutation (p.Ser150Leu) detected in a patient with non-classic 11OHD showed partial functional impairment with 19% of WT activity.ConclusionFunctional mutation analysis enables the correlation of novelCYP11B1mutations to the classic and non-classic 11OHD phenotype respectively. Mutations causing a non-classic phenotype show typically partial impairment due to reduced maximum reaction velocity comparable with non-classic mutations in 21-hydroxylase deficiency. The increasing number of mutations associated with non-classic 11OHD illustrate that this disease should be considered as diagnosis in patients with otherwise unexplained hyperandrogenism.

scholarly journals Structural Studies of TREM-2 Mutants Linked to Neurodegenerative Diseases

2014 ◽  
Vol 70 (a1) ◽  
pp. C248-C248
Author(s):  
Daniel Kober ◽  
Tom Brett
Keyword(s):  
Neurodegenerative Diseases ◽  
Neurodegenerative Disease ◽  
Structural Changes ◽  
Expression System ◽  
Point Mutations ◽  
Myeloid Cells ◽  
Surface Protein ◽  
Patient Specific ◽  
Structural Studies ◽  
Increased Risk

Triggering Receptor Expressed on Myeloid Cells-2 (TREM-2) is an extracellular surface protein expressed on myeloid cells of the monocyte/macrophage lineage including dendritic cells, macrophages, osteoclasts, and microglia. Recent genetic studies have revealed point mutations in TREM-2 that correlate with a dramatically increased risk for the development of neurodegenerative diseases, including Alzheimer's disease, frontotemporal dementia, and Parkinson's disease. This represents the first molecular link between inflammatory processes and neurodegenerative disease. TREM-2 modulates the innate immune inflammatory response; however, the biological ligand for TREM-2 remains elusive. As a first step towards understanding the role of TREM-2 in neurodegenerative disease, we have undertaken structural and biophysical studies of wild-type and mutant TREM-2 proteins. We developed a mammalian-cell based expression system for the successful production of TREM-2 in quantities suitable for structural studies. We have crystallized the TREM-2 Ig domain and determined the structure at 3.3 Å resolution. Analysis of this structure reveals the location of disease-linked mutations and produces hypotheses about their involvement in structural stability and ligand binding. In addition, we are studying the affect these mutations have on the stability of the protein using biochemical stability and surface expression assays. We are also pursuing structural studies of the point mutants to elucidate any structural changes caused by mutation. These studies are crucial to understanding the functional consequences of TREM-2 point mutations linked to the development of neurodegenerative diseases and, ultimately, to develop patient-specific molecular therapies to treat them.

scholarly journals Biosynthesis of recombinant human pro-α1(III) chains in a baculovirus expression system: production of disulphide-bonded and non-disulphide-bonded species containing full-length triple helices

1995 ◽  
Vol 312 (3) ◽  
pp. 847-853 ◽  
Author(s):  
M Tomita ◽  
N Ohkura ◽  
M Ito ◽  
T Kato ◽  
P M Royce ◽  
...  
Keyword(s):  
Insect Cells ◽  
Incubation Temperature ◽  
Expression System ◽  
Significant Proportion ◽  
Recombinant Baculovirus ◽  
Baculovirus Expression System ◽  
Dermal Fibroblasts ◽  
Full Length ◽  
Type Iii Collagen ◽  
Procollagen Iii

We have investigated the expression of human procollagen III by insect cells infected with a recombinant baculovirus carrying cDNA for the pro-alpha1(III) chain of type-III collagen. A high level of expression was obtained, and a small proportion of the heterologously expressed pro-alpha1(III) chains formed normally disulphide-bonded procollagen III, which was secreted into the culture medium. This species displayed a melting temperature (Tm) of approx. 38 degrees C as assessed by its resistance to digestion by a mixture of trypsin and chymotrypsin, slightly lower than that of 39.5 degrees C for procollagen III synthesized by cultured human dermal fibroblasts, and reflected a slight degree of under-hydroxylation of prolyl residues. This is possibly a consequence of the lower incubation temperature of insect cells, or of an insufficiency of prolyl hydroxylase activity within them. A significant proportion of the expressed chains formed trimeric molecules of similar thermal stability containing an apparently full-length triple-helical region, but were not disulphide-bonded and not secreted. In addition to providing a source of recombinant human procollagen III, the system promises to be useful in the study of procollagen chain association and subsequent folding.

scholarly journals Mutations in Rotavirus Nonstructural Glycoprotein NSP4 Are Associated with Altered Virus Virulence

1998 ◽  
Vol 72 (5) ◽  
pp. 3666-3672 ◽  
Author(s):  
Mingdong Zhang ◽  
Carl Q.-Y. Zeng ◽  
Yanjie Dong ◽  
Judith M. Ball ◽  
Linda J. Saif ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Structural Changes ◽  
Biological Activities ◽  
Expression System ◽  
Baculovirus Expression System ◽  
Nonstructural Proteins ◽  
Neonatal Mice ◽  
Life Threatening ◽  
Cloned Gene

ABSTRACT Rotaviruses are major pathogens causing life-threatening dehydrating gastroenteritis in children and animals. One of the nonstructural proteins, NSP4 (encoded by gene 10), is a transmembrane, endoplasmic reticulum-specific glycoprotein. Recently, our laboratory has shown that NSP4 causes diarrhea in 6- to 10-day-old mice by functioning as an enterotoxin. To confirm the role of NSP4 in rotavirus pathogenesis, we sequenced gene 10 from two pairs of virulent and attenuated porcine rotaviruses, the OSU and Gottfried strains. Comparisons of the NSP4 sequences from these two pairs of rotaviruses suggested that structural changes between amino acids (aa) 131 and 140 are important in pathogenesis. We next expressed the cloned gene 10 from the OSU virulent (OSU-v) and OSU attenuated (OSU-a) viruses by using the baculovirus expression system and compared the biological activities of the purified proteins. NSP4 from OSU-v virus increased intracellular calcium levels over 10-fold in intestinal cells when added exogenously and 6-fold in insect cells when expressed endogenously, whereas NSP4 from OSU-a virus had little effect. NSP4 from OSU-v caused diarrhea in 13 of 23 neonatal mice, while NSP4 from OSU-a caused disease in only 4 of 25 mice (P < 0.01). These results suggest that avirulence is associated with mutations in NSP4. Results from site-directed mutational analyses showed that mutated OSU-v NSP4 with deletion or substitutions in the region of aa 131 to 140 lost its ability to increase intracellular calcium levels and to induce diarrhea in neonatal mice, confirming the importance of amino acid changes from OSU-v NSP4 to OSU-a NSP4 in the alteration of virus virulence.

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