scholarly journals Amino Acid Substitutions in GyrA of Burkholderia glumae Are Implicated in Not Only Oxolinic Acid Resistance but Also Fitness on Rice Plants

2006 ◽  
Vol 73 (4) ◽  
pp. 1114-1119 ◽  
Author(s):  
Yukiko Maeda ◽  
Akinori Kiba ◽  
Kouhei Ohnishi ◽  
Yasufumi Hikichi
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Oxolinic Acid ◽  
The Other ◽  
Amino Acid Substitutions ◽  
Burkholderia Glumae ◽  
Field Isolates ◽  
Rice Plants ◽  
Resistant Mutants

ABSTRACT Oxolinic acid (OA) resistance in field isolates of Burkholderia glumae, a causal agent of bacterial grain rot, is dependent on an amino acid substitution at position 83 in GyrA (GyrA83). In the present study, among spontaneous in vitro mutants from the OA-sensitive B. glumae strain Pg-10, we selected OA-resistant mutants that emerged at a rate of 5.7 � 10−10. Nucleotide sequence analysis of the quinolone resistance-determining region in GyrA showed that Gly81Cys, Gly81Asp, Asp82Gly, Ser83Arg, Asp87Gly, and Asp87Asn are observed in these OA-resistant mutants. The introduction of each amino acid substitution into Pg-10 resulted in OA resistance, similar to what was observed for mutants with the responsible amino acid substitution. In vitro growth of recombinants with Asp82Gly was delayed significantly compared to that of Pg-10; however, that of the other recombinants did not differ significantly. The inoculation of each recombinant into rice spikelets did not result in disease. In inoculated rice spikelets, recombinants with Ser83Arg grew less than Pg-10 during flowering, and growth of the other recombinants was reduced significantly. On the other hand, the reduced growth of recombinants with Ser83Arg in spikelets was compensated for under OA treatment, resulting in disease. These results suggest that amino acid substitutions in GyrA of B. glumae are implicated in not only OA resistance but also fitness on rice plants. Therefore, GyrA83 substitution is thought to be responsible for OA resistance in B. glumae field isolates.

scholarly journals Virus Susceptibility Analyses from a Phase IV Clinical Trial of Inhaled Zanamivir Treatment in Children Infected with Influenza

2013 ◽  
Vol 57 (4) ◽  
pp. 1677-1684 ◽  
Author(s):  
Phillip J. Yates ◽  
Nalini Mehta ◽  
Joseph Horton ◽  
Margaret Tisdale
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Single Amino Acid ◽  
Amino Acid Substitutions ◽  
Drug Pressure ◽  
Receptor Binding Site ◽  
Virus Susceptibility ◽  
Susceptibility Data

ABSTRACTA zanamivir postapproval efficacy study was conducted in children (n= 279) in Japan during three influenza seasons. Pharyngeal swab specimens (n= 714) were obtained for detailed resistance analysis. From 371 cultured viruses, 3 viruses (A/H1N1) from two subjects showed reduced susceptibility to zanamivir at day 1 (before treatment), 1 had an N74S amino acid substitution (fold shift, 46), and 2 (day 1 and day 2) had a Q136K amino acid substitution (fold shifts, 292 and 301). Q136K was detected only in cultured virus and not in the swab. From the remaining 118 cultured viruses obtained during or after treatment with zanamivir, no shifts in virus susceptibility were detected. Neuraminidase (NA) population sequencing showed that viruses from 12 subjects had emergent amino acid substitutions, but 3 with susceptibility data were not zanamivir resistant. The remainder may be natural variants. Further analysis is planned. Hemagglutinin (HA) sequencing showed that viruses from 20 subjects had 9 HA amino acid substitutions that were previously implicated in resistance to neuraminidase inhibitors inin vitroassays or that were close to the receptor binding site. Their role inin vivoresistance appears to be less important but is not well understood. NA clonal sequence analysis was undertaken to determine if minority species of resistant viruses were present. A total of 1,682 clones from 90 subjects were analyzed. Single clones from 12 subjects contained amino acid substitutions close to the NA active site. It is unclear whether these single amino acid substitutions could have been amplified after drug pressure or are just chance mutations introduced during PCR.

scholarly journals Six point mutations that cause factor XI deficiency

Blood ◽  
1995 ◽  
Vol 85 (6) ◽  
pp. 1509-1516 ◽  
Author(s):  
RE Pugh ◽  
JH McVey ◽  
EG Tuddenham ◽  
JF Hancock
Keyword(s):  
Amino Acid ◽  
Point Mutations ◽  
Bleeding Disorder ◽  
The Other ◽  
Amino Acid Substitutions ◽  
Factor Xi ◽  
Factor Xi Deficiency ◽  
Amino Terminal ◽  
Apple Domain

We have identified six novel types of mutation that cause factor XI deficiency, an inherited bleeding disorder. Two are point mutations that interfere with the normal splicing of exons in the mRNA and four are point mutations that result in amino acid substitutions. One of these amino acid substitutions (Asp 16-->His) is near the amino terminal end of the protein. The other three amino acid substitutions (Leu 302-->Pro, Thr 304-->Ile, and Glu 323-->Lys) are in the fourth apple domain, a region that mediates dimerization of identical subunits of factor XI. All four amino acid substitutions cause a reduction in the amount of factor XI secreted from cells grown in vitro.

scholarly journals Implications of Amino Acid Substitutions in GyrA at Position 83 in Terms of Oxolinic Acid Resistance in Field Isolates of Burkholderia glumae, a Causal Agent of Bacterial Seedling Rot and Grain Rot of Rice

2004 ◽  
Vol 70 (9) ◽  
pp. 5613-5620 ◽  
Author(s):  
Yukiko Maeda ◽  
Akinori Kiba ◽  
Kouhei Ohnishi ◽  
Yasufumi Hikichi
Keyword(s):  
Amino Acid ◽  
Acid Resistance ◽  
Dna Gyrase ◽  
Oxolinic Acid ◽  
Resistant Bacteria ◽  
Rice Seedlings ◽  
Burkholderia Glumae ◽  
Field Isolates ◽  
Seedling Rot ◽  
Moderately Resistant

ABSTRACT Oxolinic acid (OA), a quinolone, inhibits the activity of DNA gyrase composed of GyrA and GyrB and shows antibacterial activity against Burkholderia glumae. Since B. glumae causes bacterial seedling rot and grain rot of rice, both of which are devastating diseases, the emergence of OA-resistant bacteria has important implications on rice cultivation in Japan. Based on the MIC of OA, 35 B. glumae field isolates isolated from rice seedlings grown from OA-treated seeds in Japan were divided into sensitive isolates (OSs; 0.5 μg/ml), moderately resistant isolates (MRs; 50 μg/ml), and highly resistant isolates (HRs; ≥100 μg/ml). Recombination with gyrA of an OS, Pg-10, led MRs and HRs to become OA susceptible, suggesting that gyrA mutations are involved in the OA resistance of field isolates. The amino acid at position 83 in the GyrA of all OSs was Ser, but in all MRs and HRs it was Arg and Ile, respectively. Ser83Arg and Ser83Ile substitutions in the GyrA of an OS, Pg-10, resulted in moderate and high OA resistance, respectively. Moreover, Arg83Ser and Ile83Ser substitutions in the GyrA of MRs and HRs, respectively, resulted in susceptibility to OA. These results suggest that Ser83Arg and Ser83Ile substitutions in GyrA are commonly responsible for resistance to OA in B. glumae field isolates.

scholarly journals Loss and Gain of Elicitor Function of Soybean Mosaic Virus G7 Provoking Rsv1-Mediated Lethal Systemic Hypersensitive Response Maps to P3

2005 ◽  
Vol 79 (2) ◽  
pp. 1215-1222 ◽  
Author(s):  
M. R. Hajimorad ◽  
A. L. Eggenberger ◽  
J. H. Hill
Keyword(s):  
Amino Acid ◽  
Mosaic Virus ◽  
Amino Acid Substitution ◽  
Hypersensitive Response ◽  
Soybean Mosaic Virus ◽  
The Other ◽  
Single Amino Acid ◽  
Amino Acid Substitutions ◽  
Extreme Resistance ◽  
Nucleotide Substitutions

ABSTRACT Rsv1, a single dominant resistance gene in soybean PI 96983 (Rsv1), confers extreme resistance against all known American strains of Soybean mosaic virus (SMV), except G7 and G7d. SMV-G7 provokes a lethal systemic hypersensitive response (LSHR), whereas SMV-G7d, an experimentally evolved variant of SMV-G7, induces systemic mosaic. To identify the elicitor of Rsv1-mediated LSHR, chimeras were constructed by exchanging fragments between the molecularly cloned SMV-G7 (pSMV-G7) and SMV-G7d (pSMV-G7d), and their elicitor functions were assessed on PI 96983 (Rsv1). pSMV-G7-derived chimeras containing only P3 of SMV-G7d lost the elicitor function, while the reciprocal chimera of pSMV-G7d gained the function. The P3 regions of the two viruses differ by six nucleotides, of which two are translationally silent. The four amino acid differences are located at positions 823, 915, 953, and 1112 of the precursor polypeptide. Analyses of the site-directed point mutants of both the viruses revealed that nucleotide substitutions leading to translationally silent mutations as well as reciprocal amino acid substitution at position 915 did not influence the loss or gain of the elicitor function. pSMV-G7-derived mutants with amino acid substitutions at any of the other three positions lost the ability to provoke LSHR but induced SHR instead. Two concomitant amino acid substitutions at positions 823 (V to M) and 953 (K to E) abolished pSMV-G7 elicitor function, provoking Rsv1-mediated SHR. Conversely, pSMV-G7d gained the elicitor function of Rsv1-mediated LSHR by a single amino acid substitution at position 823 (M to V), and mutants with amino acid substitutions at position 953 or 1112 induced SHR instead of mosaic. Taken together, the data suggest that strain-specific P3 of SMV is the elicitor of Rsv1-mediated LSHR.

scholarly journals Spread of Terbinafine-Resistant Trichophyton mentagrophytes Type VIII (India) in Germany–“The Tip of the Iceberg?”

2020 ◽  
Vol 6 (4) ◽  
pp. 207
Author(s):  
Pietro Nenoff ◽  
Shyam B. Verma ◽  
Andreas Ebert ◽  
Anke Süß ◽  
Eleni Fischer ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Indian Subcontinent ◽  
Resistance Testing ◽  
Public Health Issue ◽  
Squalene Epoxidase ◽  
Amino Acid Substitutions ◽  
Type Viii ◽  
Resistant Strains

Chronic recalcitrant dermatophytoses, due to Trichophyton (T.) mentagrophytes Type VIII are on the rise in India and are noteworthy for their predominance. It would not be wrong to assume that travel and migration would be responsible for the spread of T. mentagrophytes Type VIII from India, with many strains resistant to terbinafine, to other parts of the world. From September 2016 until March 2020, a total of 29 strains of T. mentagrophytes Type VIII (India) were isolated. All patients were residents of Germany: 12 females, 15 males and the gender of the remaining two was not assignable. Patients originated from India (11), Pakistan (two), Bangladesh (one), Iraq (two), Bahrain (one), Libya (one) and other unspecified countries (10). At least two patients were German-born residents. Most samples (21) were collected in 2019 and 2020. All 29 T. mentagrophytes isolates were sequenced (internal transcribed spacer (ITS) and translation elongation factor 1-α gene (TEF1-α)). All were identified as genotype VIII (India) of T. mentagrophytes. In vitro resistance testing revealed 13/29 strains (45%) to be terbinafine-resistant with minimum inhibitory concentration (MIC) breakpoints ≥0.2 µg/mL. The remaining 16 strains (55%) were terbinafine-sensitive. Point mutation analysis revealed that 10/13 resistant strains exhibited Phe397Leu amino acid substitution of squalene epoxidase (SQLE), indicative for in vitro resistance to terbinafine. Two resistant strains showed combined Phe397Leu and Ala448Thr amino acid substitutions, and one strain a single Leu393Phe amino acid substitution. Out of 16 terbinafine-sensitive strains, in eight Ala448Thr, and in one Ala448Thr +, new Val444 Ile amino acid substitutions were detected. Resistance to both itraconazole and voriconazole was observed in three out of 13 analyzed strains. Treatment included topical ciclopirox olamine plus topical miconazole or sertaconazole. Oral itraconazole 200 mg twice daily for four to eight weeks was found to be adequate. Terbinafine-resistant T. mentagrophytes Type VIII are being increasingly isolated. In Germany, transmission of T. mentagrophytes Type VIII from the Indian subcontinent to Europe should be viewed as a significant public health issue.

scholarly journals Molecular Characterization of Acquired Enrofloxacin Resistance in Mycoplasma synoviae Field Isolates

2013 ◽  
Vol 57 (7) ◽  
pp. 3072-3077 ◽  
Author(s):  
I. Lysnyansky ◽  
I. Gerchman ◽  
I. Mikula ◽  
F. Gobbo ◽  
S. Catania ◽  
...  
Keyword(s):  
Amino Acid ◽  
Molecular Typing ◽  
Clear Correlation ◽  
Amino Acid Substitutions ◽  
Mycoplasma Synoviae ◽  
Content Type ◽  
Field Isolates ◽  
Clear Cut

ABSTRACTThein vitroactivity of enrofloxacin against 73Mycoplasma synoviaefield strains isolated in Israel and Europe was determined by broth microdilution. Decreased susceptibility to enrofloxacin was identified in 59% of strains, with the MICs ranging from 1 to >16 μg/ml. The estimated MIC50and MIC90values for enrofloxacin were 2 and 8 μg/ml, respectively. Moreover, this study showed that 92% of recent Israeli field isolates (2009 to 2011) ofM. synoviaehave MICs of ≥2 μg/ml to enrofloxacin. Comparison of the quinolone resistance-determining regions (QRDRs) inM. synoviaeisolates revealed a clear correlation between the presence of one of the amino acid substitutions Asp79-Asn, Thr80-Ala/Ile, Ser81-Pro, and Asp84-Asn/Tyr/His of the ParC QRDR and decreased susceptibility to enrofloxacin (MIC, ≥1 μg/ml). Amino acid substitutions at positions GyrA 87, GyrB 401/402, and ParE 420/454 were also identified, but there was no clear-cut correlation with susceptibility to enrofloxacin. Comparison ofvlhAmolecular profiles revealed the presence of 9 different genotypes in the IsraeliM. synoviaefield isolates and 10 genotypes in the European isolates; only onevlhAgenotype (type 4) was identified in both cohorts. Based on results ofvlhAmolecular typing, several mechanisms for emergence and dissemination of Israeli enrofloxacin-resistantM. synoviaeisolates are suggested.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

A novel polymorphism of human gene has an amino acid substitution (V365M) that decreases enzymatic activity in vitro and in vivo

2004 ◽  
Vol 76 (6) ◽  
pp. 519-527 ◽  
Author(s):  
T FUKAMI ◽  
M NAKAJIMA ◽  
R YOSHIDA ◽  
Y TSUCHIYA ◽  
Y FUJIKI ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Substitution ◽  
Human Gene

scholarly journals Genotypic and Phenotypic Analyses of Hepatitis C Virus from Patients Treated with JTK-853 in a Three-Day Monotherapy

2012 ◽  
Vol 57 (1) ◽  
pp. 436-444 ◽  
Author(s):  
Naoki Ogura ◽  
Yukiyo Toyonaga ◽  
Izuru Ando ◽  
Kunihiro Hirahara ◽  
Tsutomu Shibata ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Viral Resistance ◽  
Hcv Rna ◽  
Amino Acid Substitutions ◽  
Sequencing Analysis ◽  
Resistance Mutations ◽  
In The Wild

ABSTRACTJTK-853, a palm site-binding NS5B nonnucleoside polymerase inhibitor, shows antiviral activityin vitroand in hepatitis C virus (HCV)-infected patients. Here, we report the results of genotypic and phenotypic analyses of resistant variants in 24 HCV genotype 1-infected patients who received JTK-853 (800, 1,200, or 1,600 mg twice daily or 1,200 mg three times daily) in a 3-day monotherapy. Viral resistance in NS5B was investigated using HCV RNA isolated from serum specimens from the patients. At the end of treatment (EOT) with JTK-853, the amino acid substitutions M414T (methionine [M] in position 414 at baseline was replaced with threonine [T] at EOT), C445R (cysteine [C] in position 445 at baseline was replaced with arginine [R] at EOT), Y448C/H (tyrosine [Y] in position 448 at baseline was replaced with cysteine [C] or histidine [H] at EOT), and L466F (leucine [L] in position 466 at baseline was replaced with phenylalanine [F] at EOT), which are known to be typical resistant variants of nonnucleoside polymerase inhibitors, were observed in a clonal sequencing analysis. These substitutions were also selected by a treatment with JTK-853in vitro, and the 50% effective concentration of JTK-853 in the M414T-, C445F-, Y448H-, and L466V-harboring replicons attenuated the susceptibility by 44-, 5-, 6-, and 21-fold, respectively, compared with that in the wild-type replicon (Con1). These findings suggest that amino acid substitutions of M414T, C445R, Y448C/H, and L466F are thought to be viral resistance mutations in HCV-infected patients receiving JTK-853 in a 3-day monotherapy.

scholarly journals TheEscherichia coliβ-Barrel Assembly Machinery Is Sensitized to Perturbations under High Membrane Fluidity

2018 ◽  
Vol 201 (1) ◽  
Author(s):  
Kelly M. Storek ◽  
Rajesh Vij ◽  
Dawei Sun ◽  
Peter A. Smith ◽  
James T. Koerber ◽  
...  
Keyword(s):  
Amino Acid ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Membrane Fluidity ◽  
Amino Acid Substitutions ◽  
Inhibitory Antibody ◽  
Critical Determinant ◽  
Gram Negative ◽  
Growth Environment

ABSTRACTIntegral β-barrel membrane proteins are folded and inserted into the Gram-negative bacterial outer membrane by the β-barrel assembly machine (BAM). This essential complex, composed of a β-barrel protein, BamA, and four lipoproteins, BamB, BamC, BamD, and BamE, resides in the outer membrane, a unique asymmetrical lipid bilayer that is difficult to recapitulatein vitro. Thus, the probing of BAM function in living cells is critical to fully understand the mechanism of β-barrel folding. We recently identified an anti-BamA monoclonal antibody, MAB1, that is a specific and potent inhibitor of BamA function. Here, we show that the inhibitory effect of MAB1 is enhanced when BAM function is perturbed by either lowering the level of BamA or removing the nonessential BAM lipoproteins, BamB, BamC, or BamE. The disruption of BAM reduces BamA activity, increases outer membrane (OM) fluidity, and activates the σEstress response, suggesting the OM environment and BAM function are interconnected. Consistent with this idea, an increase in the membrane fluidity through changes in the growth environment or alterations to the lipopolysaccharide in the outer membrane is sufficient to provide resistance to MAB1 and enable the BAM to tolerate these perturbations. Amino acid substitutions in BamA at positions in the outer membrane spanning region or the periplasmic space remote from the extracellular MAB1 binding site also provide resistance to the inhibitory antibody. Our data highlight that the outer membrane environment is a critical determinant in the efficient and productive folding of β-barrel membrane proteins by BamA.IMPORTANCEBamA is an essential component of the β-barrel assembly machine (BAM) in the outer membranes of Gram-negative bacteria. We have used a recently described inhibitory anti-BamA antibody, MAB1, to identify the molecular requirements for BAM function. Resistance to this antibody can be achieved through changes to the outer membrane or by amino acid substitutions in BamA that allosterically affect the response to MAB1. Sensitivity to MAB1 is achieved by perturbing BAM function. By using MAB1 activity and functional assays as proxies for BAM function, we link outer membrane fluidity to BamA activity, demonstrating that an increase in membrane fluidity sensitizes the cells to BAM perturbations. Thus, the search for potential inhibitors of BamA function must consider the membrane environment in which β-barrel folding occurs.

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