Amino acid modifications in the wild type sequence p53 232-240 overcome the poor immunogenicity of this self tumour epitope

2002 ◽  
Vol 8 (7) ◽  
pp. 327-334 ◽  
Author(s):  
Myriam Baratin ◽  
Mich�le Kayibanda ◽  
Marianne Ziol ◽  
Raph�elle Romieu ◽  
Jean-Paul Briand ◽  
...  
Keyword(s):  
Amino Acid ◽  
Wild Type ◽  
The Poor ◽  
Wild Type Sequence ◽  
In The Wild ◽  
Type Sequence

A highly revertible cyc1 mutant of yeast contains a small tandem duplication.

Genetics ◽  
1988 ◽  
Vol 120 (1) ◽  
pp. 57-62
Author(s):  
G Das ◽  
S Consaul ◽  
F Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Tandem Duplication ◽  
Direct Repeat ◽  
High Rate ◽  
Reversion Rate ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Wild Type Sequence ◽  
In The Wild ◽  
Type Sequence

Abstract A mutant, cyc1-96, that reverts spontaneously at an extremely high rate, was uncovered after examining approximately 500 cyc1 mutants which lack or have defective iso-1-cytochrome c in the yeast Saccharomyces cerevisiae. Cloning and DNA sequencing of appropriate fragments revealed that the cyc1-96 mutation contained a 19 bp duplication whereas the spontaneously arising revertants contained the normal wild-type sequence. Because the 19 bp segment in the wild-type sequence is flanked by a 5 bp repeat and because the cyc1-96 mutation arose spontaneously, the 19 bp duplication may have arisen by slippage and misalignment during DNA synthesis. The high reversion rate was not diminished in strains containing the rad52 mutation, which generally reduces mitotic recombination, including recombination associated with the elimination of a segment of a long direct repeat. Thus the loss of segments from short and long duplications occur by different mechanisms. We suggest that the high reversion rates of cyc1-96 and other short duplications are due to misalignment errors during replication.

Wild-Type Sequence ofTP53, Intron 7

2001 ◽  
Vol 155 (4) ◽  
pp. 641-641 ◽  
Author(s):  
Wolfgang Eicheler ◽  
Michael Baumann
Keyword(s):  
Wild Type ◽  
Wild Type Sequence ◽  
Type Sequence

The Actions of Sevoflurane and Desflurane on the γ-Aminobutyric Acid Receptor Type A

2003 ◽  
Vol 99 (3) ◽  
pp. 678-684 ◽  
Author(s):  
Koichi Nishikawa ◽  
Neil L. Harrison
Keyword(s):  
Amino Acid ◽  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Volatile Anesthetics ◽  
Aminobutyric Acid ◽  
Alpha Subunit ◽  
Induced Responses ◽  
Wild Type ◽  
In The Wild ◽  
Beta 2

Background Previous studies have shown that specific amino acid residues in the putative second transmembrane segment (TM2) of the gamma-aminobutyric acid receptor type A (GABAA) receptor play a critical role in the enhancement of GABAA receptor function by halothane, enflurane, and isoflurane. However, very little is known about the actions of sevoflurane and desflurane on recombinant GABAA receptors. The aim of this study was to examine the effects of sevoflurane and desflurane on potentiation of GABA-induced responses in the wild-type GABAA receptor and in receptors mutated in TM2 of the alpha1, alpha 2, or beta 2 subunits. Methods GABAA receptor alpha 1 or alpha 2, beta 2 or beta 3, and gamma 2s subunit cDNAs were expressed for pharmacologic study by transfection of human embryonic kidney 293 cells and assayed using the whole cell voltage clamp technique. Concentration-response curves and EC50 values for agonist were determined in the wild-type alpha 1 beta 2 gamma 2s and alpha 2 beta 3 gamma 2s receptors, and in receptors harboring mutations in TM2, such as alpha1(S270W)beta 2 gamma 2s, alpha 1 beta 2(N265W)gamma 2s, and alpha2(S270I)beta 3 gamma 2s. The actions of clinically relevant concentration of volatile anesthetics (isoflurane, sevoflurane, and desflurane) on GABA activated Cl- currents were compared in the wild-type and mutant GABAA receptors. Results Both sevoflurane and desflurane potentiated submaximal GABA currents in the wild-type GABAA alpha 1 beta 2 gamma 2s receptor and alpha 2 beta 3 gamma 2s receptor. Substitution of Ser270 in TM2 of the alpha subunit by a larger amino acid, tryptophan (W) or isoleucine (I), as in alpha1(S270W)beta 2 gamma 2s and alpha 2(S270I)beta 3 gamma 2s, completely abolished the potentiation of GABA-induced currents by these anesthetic agents. In contrast, mutation of Asn265 in TM2 of the beta subunit to tryptophan (W) did not prevent potentiation of GABA-induced responses. The actions of sevoflurane and desflurane in the wild-type receptor and in mutated receptors were qualitatively and quantitatively similar to those observed for isoflurane. Conclusions Positions Ser270 of the GABAA alpha1 and alpha2 subunits, but not Asn265 in the TM2 of the beta2 subunit, are critical for regulation of the GABAA receptor by sevoflurane and desflurane, as well as isoflurane, consistent with the idea that these three volatile anesthetics share a common site of actions on the alpha subunit of the GABAA receptor.

scholarly journals Overproduction of l-Lysine from Methanol by Methylobacillus glycogenes Derivatives Carrying a Plasmid with a Mutated dapA Gene

2001 ◽  
Vol 67 (7) ◽  
pp. 3064-3070 ◽  
Author(s):  
Hiroaki Motoyama ◽  
Hiroshi Yano ◽  
Yoko Terasaki ◽  
Hideharu Anazawa
Keyword(s):  
Amino Acid ◽  
Specific Activity ◽  
Test Tube ◽  
Amino Acid Sequences ◽  
Nutritional Requirement ◽  
Wild Type ◽  
Gene Encoding ◽  
Lysine Production ◽  
Obligate Methylotroph ◽  
In The Wild

ABSTRACT The dapA gene, encoding dihydrodipicolinate synthase (DDPS) partially desensitized to inhibition by l-lysine, was cloned from an l-threonine- andl-lysine-coproducing mutant of the obligate methylotrophMethylobacillus glycogenes DHL122 by complementation of the nutritional requirement of an Escherichia coli dapAmutant. Introduction of the dapA gene into DHL122 and AL119, which is the parent of DHL122 and an l-threonine producing mutant, elevated the specific activity of DDPS 20-fold andl-lysine production 2- to 3-fold with concomitant reduction of l-threonine in test tube cultures. AL119 containing thedapA gene produced 8 g of l-lysine per liter in a 5-liter jar fermentor from methanol as a substrate. Analysis of the nucleotide sequence of the dapA gene shows that it encodes a peptide with an M r of 30,664 and that the encoded amino acid sequence is extensively homologous to those of other organisms. In order to study the mutation that occurred in DHL122, the dapA genes of the wild type and AL119 were cloned and sequenced. Comparison of the nucleotide sequences of the dapA genes revealed that the amino acid at residue 88 was F in DHL122 whereas it was L in the wild type and AL119, suggesting that this amino acid alteration that occurred in DHL122 caused the partial desensitization of DDPS to the inhibition byl-lysine. The similarity in the amino acid sequences of DDPS in M. glycogenes and other organisms suggests that the mutation of the dapA gene in DHL122 is located in the region concerned with interaction of the allosteric effector,l-lysine.

scholarly journals Biological role of the general control of amino acid biosynthesis in Saccharomyces cerevisiae.

1981 ◽  
Vol 1 (7) ◽  
pp. 584-593 ◽  
Author(s):  
P Niederberger ◽  
G Miozzari ◽  
R Hütter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Amino Acid Biosynthesis ◽  
Wild Type ◽  
General Control ◽  
Acid Biosynthesis ◽  
Mutant Strains ◽  
In The Wild ◽  
Amino Acid Imbalance

The biological role of the "general control of amino acid biosynthesis" has been investigated by analyzing growth and enzyme levels in wild-type, bradytrophic, and nonderepressing mutant strains of Saccharomyces cerevisiae. Amino acid limitation was achieved by using either bradytrophic mutations or external amino acid imbalance. In the wild-type strain noncoordinate derepression of enzymes subject to the general control has been found. Derepressing factors were in the order of 2 to 4 in bradytrophic mutant strains grown under limiting conditions and only in the order of 1.5 to 2 under the influence of external amino acid imbalance. Nonderepressing mutations led to slower growth rates under conditions of amino acid limitation, and no derepression of enzymes under the general control was observed. The amino acid pools were found to be very similar in the wild type and in nonderepressing mutant strains under all conditions tested. Our results indicate that the general control affects all branched amino acid biosynthetic pathways, namely, those of the aromatic amino acids and the aspartate family, the pathways for the basic amino acids lysine, histidine, and arginine, and also the pathways of serine and valine biosyntheses.

scholarly journals A novel resistance pathway for calcineurin inhibitors in the human pathogenic Mucorales Mucor circinelloides

2019 ◽  
Author(s):  
Sandeep Vellanki ◽  
R. Blake Billmyre ◽  
Alejandra Lorenzen ◽  
Micaela Campbell ◽  
Broderick Turner ◽  
...  
Keyword(s):  
Amino Acid ◽  
Calcineurin Inhibitor ◽  
Calcineurin Inhibitors ◽  
Hyphal Growth ◽  
Mucor Circinelloides ◽  
Wild Type ◽  
Yeast Growth ◽  
Amino Acid Permease ◽  
In The Wild ◽  
Calcineurin Activity

AbstractMucormycosis is an emerging lethal fungal infection in immunocompromised patients. Mucor circinelloides is a causal agent of mucormycosis and serves as a model system to understand genetics in Mucorales. Calcineurin is a conserved virulence factor in many pathogenic fungi and calcineurin inhibition or deletion of the calcineurin regulatory subunit (CnbR) in Mucor results in a shift from hyphal to yeast growth. We analyzed thirty-six calcineurin inhibitor resistant or bypass mutants that exhibited hyphal growth in the presence of calcineurin inhibitors or in the yeast-locked cnbRΔ mutant background without carrying any mutations in known calcineurin components. We found that a majority of the mutants had altered sequence in a gene, named here bycA (bypass of calcineurin A). bycA encodes an amino acid permease. We verified that both bycAΔ, and the bycAΔ cnbRΔ double mutant are resistant to the calcineurin inhibitor FK506, thereby demonstrating a novel resistance mechanism against calcineurin inhibitors. We also found that the expression of bycA was significantly higher in the wild type strain treated with FK506 and in the cnbRΔ mutants, but significantly lower in the wild type without FK506. These findings suggest that bycA is a negative regulator of hyphal growth and/or a positive regulator of yeast growth in Mucor and calcineurin suppresses the bycA gene at the mRNA level to promote hyphal growth. BycA is involved in the Mucor hyphal-yeast transition as our data demonstrates a positive correlation between bycA expression, protein kinase A activity, and Mucor yeast-growth. Also calcineurin, independent of its role in morphogenesis, contributes to virulence traits including phagosome maturation blockade, host cell damages, and pro-angiogenic growth factor induction during interactions with hosts.ImportanceMucor is intrinsically resistant to most known antifungals, which makes mucormycosis treatment challenging. Calcineurin is a serine/threonine phosphatase widely conserved across eukaryotes. When calcineurin function is inhibited in Mucor, growth shifts to a less-virulent yeast growth form which makes calcineurin an attractive target for development of new antifungal drugs. Previously we identified two distinct mechanisms through which Mucor can become resistant to calcineurin inhibitors involving Mendelian mutations in the gene for FKBP12, calcineurin A or B subunits and epimutations silencing the FKBP12 gene. Here, we identified a third novel mechanism where loss of function mutations in the amino acid permease encoding the bycA gene contribute to resistance against calcineurin inhibitors. When calcineurin activity is absent, BycA can activate PKA to promote yeast growth via a cAMP-independent pathway. Our data also shows that calcineurin activity, primarily contributes to host - pathogen interactions in the pathogenesis of Mucor.

Conserved tyrosine-147 plays a critical role in the ligand-gated current of the epithelial cation/amino acid transporter/channel CAATCH1

2002 ◽  
Vol 205 (16) ◽  
pp. 2545-2553 ◽  
Author(s):  
Bruce R. Stevens ◽  
Daniel H. Feldman ◽  
Zhilin Liu ◽  
William R. Harvey
Keyword(s):  
Amino Acid ◽  
Critical Role ◽  
Amino Acid Transporter ◽  
Ionic Channel ◽  
Wild Type ◽  
Channel Conductance ◽  
Current Voltage ◽  
In The Wild ◽  
Inward Currents ◽  
Acid Transporter

SUMMARYCAATCH1 functions both as an amino-acid-gated cation channel and as a cation-dependent, proline-preferring, nutrient amino acid transporter in which the two functions are thermodynamically uncoupled. This study focuses on the ionic channel aspect, in which a Tyr147 (wild type) to Phe147 (Y147F) site-directed mutation was investigated by steady-state electrophysiological measurements in the Xenopus laevisoocyte expression system. This tyrosine residue is conserved within the third transmembrane domain in members of the Na+:neurotransmitter transporter family (SNF), where it plays a role in binding pharmacological ligands such as cocaine to the serotonin (SERT), dopamine (DAT) and norepinephrine (NET) transporters. Epithelial CAATCH1 is a member of the SNF family. The results show that amino acid ligand-gating selectivity and current magnitudes in Na+- and K+-containing media are differentially altered in CAATCH1 Y147F compared with the wild type. In the absence of amino acid ligands, the channel conductance of Na+,K+ and Li+ that is observed in the wild type was reduced to virtually zero in Y147F. In the wild type, proline binding increased conductance strongly in Na+-containing medium and moderately in K+-containing medium, whereas in Y147F proline failed to elicit any cation currents beyond those of N-methyl-D-glucamine- or water-injected oocytes. In the wild type, methionine binding strongly inhibited inward Na+ currents, whereas in Y147F it strongly stimulated inward currents in both Na+ and K+-containing media. Indeed, in Na+-containing medium, the relative potency ranking for inward current inhibition in the wild type(Met>Leu>Gly>Phe>Thr) was similar to the ranking of ligand-permissive gating of large inward currents in Y147F. In Na+-containing medium, current/voltage relationships elicited by ligands in the wild type were complex and reversing, whereas in Y147F they were linear and inwardly rectifying. In K+-containing medium,current/voltage relationships remained non-linear in Y147F. Both wild-type and Y147F currents were Cl--independent. Together, these data demonstrate a critical role for Tyr147 in ligand-binding selectivity and modulation of the ionic channel conductance in CAATCH1. The results support the argument that inhibition of the CAATCH1 conductance by free methionine shares some properties in common with ligand inhibition of DAT, SERT, NET and the γ-aminobutyric acid transporter (GAT1).

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