scholarly journals A single lysine in the N-terminal region of store-operated channels is critical for STIM1-mediated gating

2010 ◽  
Vol 136 (6) ◽  
pp. 673-686 ◽  
Author(s):  
Annette Lis ◽  
Susanna Zierler ◽  
Christine Peinelt ◽  
Andrea Fleig ◽  
Reinhold Penner
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Calcium Release ◽  
Transmembrane Domain ◽  
Single Point ◽  
Point Mutations ◽  
Terminal Region ◽  
Single Amino Acid ◽  
Critical Element ◽  
Crac Channels

Store-operated Ca2+ entry is controlled by the interaction of stromal interaction molecules (STIMs) acting as endoplasmic reticulum ER Ca2+ sensors with calcium release–activated calcium (CRAC) channels (CRACM1/2/3 or Orai1/2/3) in the plasma membrane. Here, we report structural requirements of STIM1-mediated activation of CRACM1 and CRACM3 using truncations, point mutations, and CRACM1/CRACM3 chimeras. In accordance with previous studies, truncating the N-terminal region of CRACM1 or CRACM3 revealed a 20–amino acid stretch close to the plasma membrane important for channel gating. Exchanging the N-terminal region of CRACM3 with that of CRACM1 (CRACM3-N(M1)) results in accelerated kinetics and enhanced current amplitudes. Conversely, transplanting the N-terminal region of CRACM3 into CRACM1 (CRACM1-N(M3)) leads to severely reduced store-operated currents. Highly conserved amino acids (K85 in CRACM1 and K60 in CRACM3) in the N-terminal region close to the first transmembrane domain are crucial for STIM1-dependent gating of CRAC channels. Single-point mutations of this residue (K85E and K60E) eliminate store-operated currents induced by inositol 1,4,5-trisphosphate and reduce store-independent gating by 2-aminoethoxydiphenyl borate. However, short fragments of these mutant channels are still able to communicate with the CRAC-activating domain of STIM1. Collectively, these findings identify a single amino acid in the N terminus of CRAC channels as a critical element for store-operated gating of CRAC channels.

scholarly journals Intrinsic resistance to terbinafine among human and animal isolates of Trichophyton mentagrophytes related to amino acid substitution in the squalene epoxidase

Infection ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Dominik Łagowski ◽  
Sebastian Gnat ◽  
Aneta Nowakiewicz ◽  
Marcelina Osińska ◽  
Mariusz Dyląg
Keyword(s):  
Amino Acid ◽  
Fungal Infections ◽  
Single Point ◽  
Antifungal Susceptibility ◽  
Point Mutations ◽  
Trichophyton Mentagrophytes ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Intrinsic Resistance ◽  
Resistant Strains

Abstract Background Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway. Purpose Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland. Methods We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed. Results In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin. Conclusion Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

scholarly journals Novel isoform of syntaxin 1 is expressed in mammalian cells

1997 ◽  
Vol 321 (1) ◽  
pp. 151-156 ◽  
Author(s):  
Mittur N. JAGADISH ◽  
Judy T. TELLAM ◽  
S. Lance MACAULAY ◽  
Keith H. GOUGH ◽  
David E. JAMES ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Cdna Clone ◽  
Mammalian Cells ◽  
Transmembrane Domain ◽  
Terminal Region ◽  
Receptor Protein ◽  
Fat Cell ◽  
Syntaxin 1A ◽  
Truncated Protein

Syntaxin 1A has been identified previously as a neural-cell-specific, membrane-anchored receptor protein required for docking and fusion of synaptic vesicles with the presynaptic plasma membrane. Syntaxin 1A consists of 288 amino acid residues including a 265-residue N-terminal region exposed to the cytoplasm and a C-terminal hydrophobic stretch of 23 residues believed to anchor syntaxin to the plasma membrane. Using a human fat-cell library we have isolated a novel cDNA clone of syntaxin 1A containing an insert of 91 bp in codon 226. This insert and subsequent frame shift generated a cDNA that codes for a truncated protein of 260 residues without the C-terminal transmembrane domain characteristic of the syntaxin family. Analysis of the deduced amino acid sequence of the new cDNA clone, termed syntaxin 1C, showed that it was identical for the first 226 residues with the previously described neural syntaxin 1A, and diverged thereafter. The truncated protein lacked the botulinum neurotoxin C cleavage site (Lys253-Ala254), a feature of the syntaxin 1A protein, because of the novel C-terminal domain of 34 residues. The new C-terminal region contained a single cysteine residue and was moderately rich in proline, with three repeats of a PXP motif. The insert occurred within the region encoding the coiled-coil motifs required for interactions with synaptobrevin, α-SNAP (SNAP being soluble N-ethylmaleimide-sensitive factor attachment protein) and n-Sec1/Munc-18 (n-Sec1 being the rat brain homologue of yeast Sec1p and Munc-18 the mammalian homologue of Caenorhabditis elegans unc-18, but five residues outside the domain previously mapped as being required for binding SNAP-25. Interaction studies in vitro suggested that unlike syntaxin 1A, which binds to both Munc-18a and -18b, syntaxin 1C binds only to Munc-18b. The new isoform syntaxin 1C, which might be generated by alternative splicing of the syntaxin 1 gene, was expressed in several human tissues, including brain. Immunoprecipitation and immunoblotting with the monoclonal antibody HPC-1 and a polyclonal antibody raised against a peptide corresponding to the unique C-terminal 35 residues of syntaxin 1C failed to detect syntaxin 1C at the protein level in extracts of muscle, fat or brain.

scholarly journals Tuning Structure and Dynamics of Blue Copper Azurin Junctions via Single Amino-Acid Mutations

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 611 ◽  
Author(s):  
Ortega ◽  
Vilhena ◽  
Zotti ◽  
Díez-Pérez ◽  
Cuevas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Single Molecule ◽  
Single Point ◽  
Point Mutations ◽  
Point Of View ◽  
Single Amino Acid ◽  
Theoretical Point ◽  
Blue Copper ◽  
Structure And Dynamics ◽  
Amino Acid Mutations

In the growing field of biomolecular electronics, blue-copper Azurin stands out as one of the most widely studied protein in single-molecule contacts. Interestingly, despite the paramount importance of the structure/dynamics of molecular contacts in their transport properties, these factors remain largely unexplored from the theoretical point of view in the context of single Azurin junctions. Here we address this issue using all-atom Molecular Dynamics (MD) of Pseudomonas Aeruginosa Azurin adsorbed to a Au(111) substrate. In particular, we focus on the structure and dynamics of the free/adsorbed protein and how these properties are altered upon single-point mutations. The results revealed that wild-type Azurin adsorbs on Au(111) along two well defined configurations: one tethered via cysteine groups and the other via the hydrophobic pocket surrounding the Cu 2 + . Surprisingly, our simulations revealed that single amino-acid mutations gave rise to a quenching of protein vibrations ultimately resulting in its overall stiffening. Given the role of amino-acid vibrations and reorientation in the dehydration process at the protein-water-substrate interface, we suggest that this might have an effect on the adsorption process of the mutant, giving rise to new adsorption configurations.

scholarly journals Terbinafine Resistance of Trichophyton Clinical Isolates Caused by Specific Point Mutations in the Squalene Epoxidase Gene

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Tsuyoshi Yamada ◽  
Mari Maeda ◽  
Mohamed Mahdi Alshahni ◽  
Reiko Tanaka ◽  
Takashi Yaguchi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Single Point ◽  
Point Mutations ◽  
Trichophyton Mentagrophytes ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Amino Acid Substitutions ◽  
Content Type

ABSTRACT Terbinafine is one of the allylamine antifungal agents whose target is squalene epoxidase (SQLE). This agent has been extensively used in the therapy of dermatophyte infections. The incidence of patients with tinea pedis or unguium tolerant to terbinafine treatment prompted us to screen the terbinafine resistance of all Trichophyton clinical isolates from the laboratory of the Centre Hospitalier Universitaire Vaudois collected over a 3-year period and to identify their mechanism of resistance. Among 2,056 tested isolates, 17 (≈1%) showed reduced terbinafine susceptibility, and all of these were found to harbor SQLE gene alleles with different single point mutations, leading to single amino acid substitutions at one of four positions (Leu393, Phe397, Phe415, and His440) of the SQLE protein. Point mutations leading to the corresponding amino acid substitutions were introduced into the endogenous SQLE gene of a terbinafine-sensitive Arthroderma vanbreuseghemii (formerly Trichophyton mentagrophytes) strain. All of the generated A. vanbreuseghemii transformants expressing mutated SQLE proteins exhibited obvious terbinafine-resistant phenotypes compared to the phenotypes of the parent strain and of transformants expressing wild-type SQLE proteins. Nearly identical phenotypes were also observed in A. vanbreuseghemii transformants expressing mutant forms of Trichophyton rubrum SQLE proteins. Considering that the genome size of dermatophytes is about 22 Mb, the frequency of terbinafine-resistant clinical isolates was strikingly high. Increased exposure to antifungal drugs could favor the generation of resistant strains.

scholarly journals A Single Point Mutation, Asn16→Lys, Dictates the Temperature-Sensitivity of the Reovirus tsG453 Mutant

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 289
Author(s):  
Kathleen K. M. Glover ◽  
Danica M. Sutherland ◽  
Terence S. Dermody ◽  
Kevin M. Coombs
Keyword(s):  
Amino Acid ◽  
Temperature Sensitivity ◽  
Reverse Genetics ◽  
Core Protein ◽  
Single Point ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Temperature Sensitive ◽  
Amino Acid Substitutions ◽  
Gene Encoding

Studies of conditionally lethal mutants can help delineate the structure-function relationships of biomolecules. Temperature-sensitive (ts) mammalian reovirus (MRV) mutants were isolated and characterized many years ago. Two of the most well-defined MRV ts mutants are tsC447, which contains mutations in the S2 gene encoding viral core protein σ2, and tsG453, which contains mutations in the S4 gene encoding major outer-capsid protein σ3. Because many MRV ts mutants, including both tsC447 and tsG453, encode multiple amino acid substitutions, the specific amino acid substitutions responsible for the ts phenotype are unknown. We used reverse genetics to recover recombinant reoviruses containing the single amino acid polymorphisms present in ts mutants tsC447 and tsG453 and assessed the recombinant viruses for temperature-sensitivity by efficiency-of-plating assays. Of the three amino acid substitutions in the tsG453 S4 gene, Asn16-Lys was solely responsible for the tsG453ts phenotype. Additionally, the mutant tsC447 Ala188-Val mutation did not induce a temperature-sensitive phenotype. This study is the first to employ reverse genetics to identify the dominant amino acid substitutions responsible for the tsC447 and tsG453 mutations and relate these substitutions to respective phenotypes. Further studies of other MRV ts mutants are warranted to define the sequence polymorphisms responsible for temperature sensitivity.

scholarly journals Characterization of an enhanced antigenic change in the pandemic 2009 H1N1 influenza virus haemagglutinin

2014 ◽  
Vol 95 (5) ◽  
pp. 1033-1042 ◽  
Author(s):  
Blanca García-Barreno ◽  
Teresa Delgado ◽  
Sonia Benito ◽  
Inmaculada Casas ◽  
Francisco Pozo ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Influenza A ◽  
Point Mutations ◽  
Antigenic Site ◽  
Single Amino Acid ◽  
Antigenic Structure ◽  
Human Antibody ◽  
2009 H1n1

Murine hybridomas producing neutralizing mAbs specific to the pandemic influenza virus A/California/07/2009 haemagglutinin (HA) were isolated. These antibodies recognized at least two different but overlapping new epitopes that were conserved in the HA of most Spanish pandemic isolates. However, one of these isolates (A/Extremadura/RR6530/2010) lacked reactivity with the mAbs and carried two unique mutations in the HA head (S88Y and K136N) that were required simultaneously to eliminate reactivity with the murine antibodies. This unusual requirement directly illustrates the phenomenon of enhanced antigenic change proposed previously for the accumulation of simultaneous amino acid substitutions at antigenic sites of the influenza A virus HA during virus evolution (Shih et al., Proc Natl Acad Sci USA, 104 , 6283–6288, 2007). The changes found in the A/Extremadura/RR6530/2010 HA were not found in escape mutants selected in vitro with one of the mAbs, which contained instead nearby single amino acid changes in the HA head. Thus, either single or double point mutations may similarly alter epitopes of the new antigenic site identified in this work in the 2009 H1N1 pandemic virus HA. Moreover, this site is relevant for the human antibody response, as shown by competition of mAbs and human post-infection sera for virus binding. The results are discussed in the context of the HA antigenic structure and challenges posed for identification of sequence changes with possible antigenic impact during virus surveillance.

scholarly journals C-Terminal Region of STAT-1α Is Not Necessary for Its Ubiquitination and Degradation Caused by Mumps Virus V Protein

2002 ◽  
Vol 76 (24) ◽  
pp. 12683-12690 ◽  
Author(s):  
Noriko Yokosawa ◽  
Shin-ichi Yokota ◽  
Toru Kubota ◽  
Nobuhiro Fujii
Keyword(s):  
Amino Acid ◽  
Transcriptional Activation ◽  
Tandem Repeats ◽  
Mumps Virus ◽  
Terminal Region ◽  
Single Amino Acid ◽  
Luciferase Reporter ◽  
Enhancer Element ◽  
V Protein ◽  
Gene Assay

ABSTRACT Constitutive levels of production of STAT-1 were reduced by 10 h postinfection (p.i.) and significantly lost by 24 h p.i. in FL cells acutely infected with mumps virus (MuV). This result was consistent with that observed in previous studies and experiments with cells persistently infected with MuV (FLMT cells). There was a marked decrease in the amount of STAT-1 in cells expressing MuV accessory protein V (MuV-V). Furthermore, single amino acid substitutions in the Cys-rich region of V protein (Vc189a, Vc207a, and Vc214a) showed that each cysteine residue plays an important role in the decrease in STAT-1 production, but substitution of a histidine residue at amino acid position 203 had no effect. These events and the resultant suppression of the alpha interferon (IFN-α) response were confirmed by a luciferase reporter gene assay with five tandem repeats of the IFN-α-stimulated response element as an enhancer element of the firely luciferase gene. STAT-1 production was restored and detectable in FLMT cells treated with a proteosome inhibitor, such as MG132 or lactacystin. In the presence of MG132, ubiquitination of STAT-1 and the interaction of MuV-V with STAT-1 were demonstrated in FLMT cells by immunoprecipitation with anti-STAT-1 antibody. The same results for the interaction and ubiquitination were obtained in experiments with an expression vector for a C-terminal deletion mutant of STAT-1. The truncated STAT-1 molecules were degraded in the presence of MuV-V. Therefore, the C-terminal region (transcriptional activation and Src homology 2 domains) of STAT-1 is not necessary for its degradation caused by MuV-V. Our data suggest that MuV-V promotes ubiquitination and degradation of STAT-1.

scholarly journals Identification of separate domains in the adenovirus E1A gene for immortalization activity and the activation of virus early genes.

1986 ◽  
Vol 6 (10) ◽  
pp. 3470-3480 ◽  
Author(s):  
E Moran ◽  
B Zerler ◽  
T M Harrison ◽  
M B Mathews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Point Mutations ◽  
Apparent Molecular Weight ◽  
Amino Acid Position ◽  
Cysteine Residue ◽  
Transformation Function ◽  
Single Amino Acid ◽  
Amino Acid Substitutions ◽  
E1a Gene

The transformation and early adenovirus gene transactivation functions of the E1A region were analyzed with deletion and point mutations. Deletion of amino acids from position 86 through 120 had little effect on the lytic or transforming functions of the E1A products, while deletion of amino acids from position 121 through 150 significantly impaired both functions. The sensitivity of the transformation function to alterations in the region from amino acid position 121 to 150 was further indicated by the impairment of transforming activity resulting from single amino acid substitutions at positions 124 and 135. Interestingly, conversion of a cysteine residue at position 124 to glycine severely impaired the transformation function without affecting the early adenovirus gene activating functions. Single amino acid substitutions in a different region of the E1A gene had the converse effect. All the mutants produced polypeptides of sufficient stability to be detected by Western immunoblot analysis. The single amino acid substitutions at positions 124 and 135, although impairing the transformation functions, did not detectably alter the formation of the higher-apparent-molecular-weight forms of the E1A products.

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