Beaded of Goldschmidt, an Antimorphic Allele of Serrate, Encodes a Protein Lacking Transmembrane and Intracellular Domains

Genetics ◽  
1997 ◽  
Vol 145 (2) ◽  
pp. 359-374 ◽  
Author(s):  
Neil A Hukriede ◽  
Robert J Fleming
Keyword(s):  
Essential Gene ◽  
Protein Product ◽  
Homologous Region ◽  
Wing Margin ◽  
Loss Of Function ◽  
Wild Type ◽  
Rich Region ◽  
Coding Regions ◽  
Dna Lesion ◽  
Intracellular Domains

Serrate (Ser) is an essential gene in Drosophila melanogaster best known for the Ser dominant (SerD) allele and its effects on wing development. Animals heterozygous or homozygous for (SerD) are viable and exhibit loss of wing margin tissue and associated bristles and hairs. The Beaded of Goldschmidt (BdG) allele of Ser, when heterozygous to wild type, will also produce animals exhibiting loss of wing margin material. However, animals homozygous for BdG exhibit a larval lethal phenotype comparable to animals homozygous for loss-of-function Ser alleles. BdG is a partial duplication of the Ser locus with a single 5′ Ser-homologous region and two distinct 3′ regions. Meiotic recombination between BdG and a wild-type Ser chromosome demonstrated that only one DNA lesion, caused by the insertion of a transposable roo element into the coding regions of the Ser transcript, appears capable of generating BdG phenotypes. Due to the roo insertion, the protein product is predicted to be prematurely truncated and lack an extracellular cysteine-rich region along with the transmembrane and intracellular domains found within the normal SERRATE (SER) protein. The loss of these protein domains apparently contributes to the antimorphic nature of this mutation.

scholarly journals Genetic interactions between the Drosophila Abelson (Abl) tyrosine kinase and failed axon connections (fax), a novel protein in axon bundles.

Genetics ◽  
1995 ◽  
Vol 141 (2) ◽  
pp. 595-606 ◽  
Author(s):  
K K Hill ◽  
V Bedian ◽  
J L Juang ◽  
F M Hoffmann
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Essential Gene ◽  
Protein Product ◽  
Genetic Interactions ◽  
Loss Of Function ◽  
Wild Type ◽  
Abl Tyrosine Kinase ◽  
The Central Nervous System ◽  
Novel Protein

Abstract Mutations in the failed axon connections (fax) gene have been identified as dominant genetic enhancers of the Abl mutant phenotype. These mutations in fax all result in defective or absent protein product. In a genetic background with wild-type Abl function, the fax loss-of-function alleles are homozygous viable, demonstrating that fax is not an essential gene unless the animal is also mutant for Abl. The fax gene encodes a novel 47-kD protein expressed in a developmental pattern similar to that of Abl in the embryonic mesoderm and axons of the central nervous system. The conditional, extragenic noncomplementation between fax and another Abl modifier gene, disabled, reveal that the two proteins are likely to function together in a process downstream or parallel to the Abl protein tyrosine kinase.

DNA sequence, structure, and tyrosine kinase activity of the Drosophila melanogaster Abelson proto-oncogene homolog

1988 ◽  
Vol 8 (2) ◽  
pp. 843-853
Author(s):  
M J Henkemeyer ◽  
R L Bennett ◽  
F B Gertler ◽  
F M Hoffmann
Keyword(s):  
Drosophila Melanogaster ◽  
Tyrosine Kinase ◽  
Dna Sequence ◽  
Kinase Activity ◽  
Essential Gene ◽  
Sequence Similarity ◽  
Homologous Region ◽  
Loss Of Function ◽  
Tyrosine Kinase Activity ◽  
Stage Of Development

We report our molecular characterization of the Drosophila melanogaster Abelson gene (abl), a gene in which recessive loss-of-function mutations result in lethality at the pupal stage of development. This essential gene consists of 10 exons extending over 26 kilobase pairs of genomic DNA. The DNA sequence encodes a protein of 1,520 amino acids with strong sequence similarity to the human c-abl proto-oncogene beginning in the type lb 5' exon and extending through the region essential for tyrosine kinase activity. When the tyrosine kinase homologous region was expressed in Escherichia coli, phosphorylation of proteins on tyrosine residues was observed with an antiphosphotyrosine antibody. These results show that the abl gene is highly conserved through evolution and encodes a functional tyrosine protein kinase required for Drosophila development.

scholarly journals A deep intronic splice mutation of STAT3 underlies hyper IgE syndrome by negative dominance

2019 ◽  
Vol 116 (33) ◽  
pp. 16463-16472 ◽  
Author(s):  
Joëlle Khourieh ◽  
Geetha Rao ◽  
Tanwir Habib ◽  
Danielle T. Avery ◽  
Alain Lefèvre-Utile ◽  
...  
Keyword(s):  
Dominant Negative ◽  
Loss Of Function ◽  
Wild Type ◽  
Dominant Form ◽  
Mutant Proteins ◽  
Coding Regions ◽  
Hyper Ige Syndrome ◽  
Autosomal Dominant Form ◽  
Negative Dominance ◽  
B And T Lymphocytes

Heterozygous in-frame mutations in coding regions of human STAT3 underlie the only known autosomal dominant form of hyper IgE syndrome (AD HIES). About 5% of familial cases remain unexplained. The mutant proteins are loss-of-function and dominant-negative when tested following overproduction in recipient cells. However, the production of mutant proteins has not been detected and quantified in the cells of heterozygous patients. We report a deep intronic heterozygous STAT3 mutation, c.1282-89C>T, in 7 relatives with AD HIES. This mutation creates a new exon in the STAT3 complementary DNA, which, when overexpressed, generates a mutant STAT3 protein (D427ins17) that is loss-of-function and dominant-negative in terms of tyrosine phosphorylation, DNA binding, and transcriptional activity. In immortalized B cells from these patients, the D427ins17 protein was 2 kDa larger and 4-fold less abundant than wild-type STAT3, on mass spectrometry. The patients’ primary B and T lymphocytes responded poorly to STAT3-dependent cytokines. These findings are reminiscent of the impaired responses of leukocytes from other patients with AD HIES due to typical STAT3 coding mutations, providing further evidence for the dominance of the mutant intronic allele. These findings highlight the importance of sequencing STAT3 introns in patients with HIES without candidate variants in coding regions and essential splice sites. They also show that AD HIES-causing STAT3 mutant alleles can be dominant-negative even if the encoded protein is produced in significantly smaller amounts than wild-type STAT3.

scholarly journals DNA sequence, structure, and tyrosine kinase activity of the Drosophila melanogaster Abelson proto-oncogene homolog.

1988 ◽  
Vol 8 (2) ◽  
pp. 843-853 ◽  
Author(s):  
M J Henkemeyer ◽  
R L Bennett ◽  
F B Gertler ◽  
F M Hoffmann
Keyword(s):  
Drosophila Melanogaster ◽  
Tyrosine Kinase ◽  
Dna Sequence ◽  
Kinase Activity ◽  
Essential Gene ◽  
Sequence Similarity ◽  
Homologous Region ◽  
Loss Of Function ◽  
Tyrosine Kinase Activity ◽  
Stage Of Development

We report our molecular characterization of the Drosophila melanogaster Abelson gene (abl), a gene in which recessive loss-of-function mutations result in lethality at the pupal stage of development. This essential gene consists of 10 exons extending over 26 kilobase pairs of genomic DNA. The DNA sequence encodes a protein of 1,520 amino acids with strong sequence similarity to the human c-abl proto-oncogene beginning in the type lb 5' exon and extending through the region essential for tyrosine kinase activity. When the tyrosine kinase homologous region was expressed in Escherichia coli, phosphorylation of proteins on tyrosine residues was observed with an antiphosphotyrosine antibody. These results show that the abl gene is highly conserved through evolution and encodes a functional tyrosine protein kinase required for Drosophila development.

The intracellular deletions of Delta and Serrate define dominant negative forms of the Drosophila Notch ligands

Development ◽  
1996 ◽  
Vol 122 (8) ◽  
pp. 2465-2474 ◽  
Author(s):  
X. Sun ◽  
S. Artavanis-Tsakonas
Keyword(s):  
Notch Pathway ◽  
Notch Signalling ◽  
Dominant Negative ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Wild Type ◽  
Mutant Forms ◽  
Intracellular Domains ◽  
Notch Ligands ◽  
Enhancer Of Split

We examined the function of the intracellular domains of the two known Drosophila Notch ligands, Delta and Serrate, by expressing wild-type and mutant forms in the developing Drosophila eye under the sevenless promoter. The expression of intracellularly truncated forms of either Delta (sev-DlTM) or Serrate (sev-SerTM) leads to extra photoreceptor phenotypes, similar to the eye phenotypes associated with loss-of-function mutations of either Notch or Delta. Consistent with the notion that the truncated ligands reduce. Notch signalling activity, the eye phenotypes of sev-DlTM and sev-SerTM are enhanced by loss-of-function mutations in the Notch pathway elements, Notch, Delta, mastermind, deltex and groucho, but are suppressed by a duplication of Delta or mutations in Hairless, a negative regulator of the pathway. These observations were extended to the molecular level by demonstrating that the expression of Enhancer of split m delta, a target of Notch signalling, is down-regulated by the truncated ligands highly expressed in neighbouring cells. We conclude that the truncated ligands act as antagonists of Notch signalling.

LdARL-3A, a Leishmania promastigote-specific ADP-ribosylation factor-like protein, is essential for flagellum integrity

2000 ◽  
Vol 113 (11) ◽  
pp. 2065-2074 ◽  
Author(s):  
A. Cuvillier ◽  
F. Redon ◽  
J.C. Antoine ◽  
P. Chardin ◽  
T. DeVos ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Leishmania Donovani ◽  
Essential Gene ◽  
Active Form ◽  
Protein Product ◽  
Immune Serum ◽  
Wild Type ◽  
Extracellular Medium ◽  
Western Blots ◽  
Slow Growth Rate

The small G protein-encoding LdARL-3A gene, a homologue of the human ARL-3 gene, was isolated from Leishmania donovani, and its protein product characterised. It is unique in the Leishmania genome and expressed only in the extracellular promastigote insect form, but not in the intracellular amastigote mammalian form, as shown by northern blots and western blots developed with a specific anti-C terminus immune serum. Indirect immunofluorescence microscopy revealed distinct labelled spots regularly distributed on the plasma membrane, including the part lining the flagellum and the flagellar pocket. By transfection experiments, it was found that wild-type LdARL-3A-overexpressing promastigotes reached higher densities in culture, but released significantly less secreted acid phosphatase in the extracellular medium than the parental strain. When LdARL-3A blocked under the GDP-bound ‘inactive’ form or with an inactivated potential myristoylation site was overexpressed, the cells displayed an apparent wild-type phenotype, but died earlier in the stationary phase; in contrast to parental cells, they showed a diffuse pattern of fluorescence labelling in the cytoplasm and on the cell membrane. Strikingly, when a constitutively ‘active’ form of LdARL-3A (blocked under the GTP-bound form) was overexpressed, the promastigotes were immobile with a very short flagellum, a slow growth rate and a low level of acid phosphatase secretion; the length of the flagellum was inversely proportional to mutant protein expression. We concluded that LdARL-3A could be an essential gene involved in flagellum biogenesis; it may provide new approaches for control of the parasite at the insect stage.

scholarly journals Lethal (2) giant discs (Lgd)/CC2D1 is required for the full activity of the ESCRT machinery

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Miriam Baeumers ◽  
Kristina Ruhnau ◽  
Thomas Breuer ◽  
Hendrik Pannen ◽  
Bastian Goerlich ◽  
...  
Keyword(s):  
Transmembrane Proteins ◽  
Loss Of Function ◽  
Wild Type ◽  
Endosomal Sorting ◽  
Full Activity ◽  
Complete Degradation ◽  
Escrt Machinery ◽  
Intracellular Domains ◽  
Mutant Cells ◽  
Reduced Activity

Abstract Background A major task of the endosomal sorting complex required for transport (ESCRT) machinery is the pinching off of cargo-loaded intraluminal vesicles (ILVs) into the lumen of maturing endosomes (MEs), which is essential for the complete degradation of transmembrane proteins in the lysosome. The ESCRT machinery is also required for the termination of signalling through activated signalling receptors, as it separates their intracellular domains from the cytosol. At the heart of the machinery lies the ESCRT-III complex, which is required for an increasing number of processes where membrane regions are abscised away from the cytosol. The core of ESCRT-III, comprising four members of the CHMP protein family, organises the assembly of a homopolymer of CHMP4, Shrub in Drosophila, that is essential for abscission. We and others identified the tumour-suppressor lethal (2) giant discs (Lgd)/CC2D1 as a physical interactor of Shrub/CHMP4 in Drosophila and mammals, respectively. Results Here, we show that the loss of function of lgd constitutes a state of reduced activity of Shrub/CHMP4/ESCRT-III. This hypomorphic shrub mutant situation causes a slight decrease in the rate of ILV formation that appears to result in incomplete incorporation of Notch into ILVs. We found that the forced incorporation in ILVs of lgd mutant MEs suppresses the uncontrolled and ligand-independent activation of Notch. Moreover, the analysis of Su(dx) lgd double mutants clarifies their relationship and suggests that they are not operating in a linear pathway. We could show that, despite prolonged lifetime, the MEs of lgd mutants have a similar ILV density as wild-type but less than rab7 mutant MEs, suggesting the rate in lgd mutants is slightly reduced. The analysis of the MEs of wild-type and mutant cells in the electron microscope revealed that the ESCRT-containing electron-dense microdomains of ILV formation at the limiting membrane are elongated, indicating a change in ESCRT activity. Since lgd mutants can be rescued to normal adult flies if extra copies of shrub (or its mammalian ortholog CHMP4B) are added into the genome, we conclude that the net activity of Shrub is reduced upon loss of lgd function. Finally, we show that, in solution, CHMP4B/Shrub exists in two conformations. LGD1/Lgd binding does not affect the conformational state of Shrub, suggesting that Lgd is not a chaperone for Shrub/CHMP4B. Conclusion Our results suggest that Lgd is required for the full activity of Shrub/ESCRT-III. In its absence, the activity of the ESCRT machinery is reduced. This reduction causes the escape of a fraction of cargo, among it Notch, from incorporation into ILVs, which in turn leads to an activation of this fraction of Notch after fusion of the ME with the lysosome. Our results highlight the importance of the incorporation of Notch into ILV not only to assure complete degradation, but also to avoid uncontrolled activation of the pathway.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals The NALCN Channel Regulator UNC-80 Functions in a Subset of Interneurons To Regulate Caenorhabditis elegans Reversal Behavior

2019 ◽  
Vol 10 (1) ◽  
pp. 199-210 ◽  
Author(s):  
Chuanman Zhou ◽  
Jintao Luo ◽  
Xiaohui He ◽  
Qian Zhou ◽  
Yunxia He ◽  
...  
Keyword(s):  
Plant Hormone ◽  
Neuronal Excitability ◽  
Resting Membrane Potential ◽  
Loss Of Function ◽  
Wild Type ◽  
C Elegans ◽  
Link Type ◽  
Complex Functions ◽  
And Function ◽  
Multiple Loss

NALCN (Na+leak channel, non-selective) is a conserved, voltage-insensitive cation channel that regulates resting membrane potential and neuronal excitability. UNC79 and UNC80 are key regulators of the channel function. However, the behavioral effects of the channel complex are not entirely clear and the neurons in which the channel functions remain to be identified. In a forward genetic screen for C. elegans mutants with defective avoidance response to the plant hormone methyl salicylate (MeSa), we isolated multiple loss-of-function mutations in unc-80 and unc-79. C. elegans NALCN mutants exhibited similarly defective MeSa avoidance. Interestingly, NALCN, unc-80 and unc-79 mutants all showed wild type-like responses to other attractive or repelling odorants, suggesting that NALCN does not broadly affect odor detection or related forward and reversal behaviors. To understand in which neurons the channel functions, we determined the identities of a subset of unc-80-expressing neurons. We found that unc-79 and unc-80 are expressed and function in overlapping neurons, which verified previous assumptions. Neuron-specific transgene rescue and knockdown experiments suggest that the command interneurons AVA and AVE and the anterior guidepost neuron AVG can play a sufficient role in mediating unc-80 regulation of the MeSa avoidance. Though primarily based on genetic analyses, our results further imply that MeSa might activate NALCN by direct or indirect actions. Altogether, we provide an initial look into the key neurons in which the NALCN channel complex functions and identify a novel function of the channel in regulating C. elegans reversal behavior through command interneurons.

scholarly journals Identification of a novel homozygous loss-of-function mutation in FUCA1 gene causing severe fucosidosis: A case report

2021 ◽  
Vol 49 (4) ◽  
pp. 030006052110059
Author(s):  
Xinwen Zhang ◽  
Shaozhi Zhao ◽  
Hongwei Liu ◽  
Xiaoyan Wang ◽  
Xiaolei Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lysosomal Storage Disorder ◽  
Autosomal Recessive ◽  
Signs And Symptoms ◽  
Lysosomal Storage ◽  
Loss Of Function ◽  
Wild Type ◽  
Single Nucleotide ◽  
Whole Exome ◽  
Exon 1

Fucosidosis is a rare lysosomal storage disorder characterized by deficiency of α-L-fucosidase with an autosomal recessive mode of inheritance. Here, we describe a 4-year-old Chinese boy with signs and symptoms of fucosidosis but his parents were phenotypically normal. Whole exome sequencing (WES) identified a novel homozygous single nucleotide deletion (c.82delG) in the exon 1 of the FUCA1 gene. This mutation will lead to a frameshift which will result in the formation of a truncated FUCA1 protein (p.Val28Cysfs*105) of 132 amino acids approximately one-third the size of the wild type FUCA1 protein (466 amino acids). Both parents were carrying the mutation in a heterozygous state. This study expands the mutational spectrum of the FUCA1 gene associated with fucosidosis and emphasises the benefits of WES for accurate and timely clinical diagnosis of this rare disease.

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