scholarly journals Amino Acid Sequence Requirements in the Hinge of Human Immunoglobulin A1 (IgA1) for Cleavage by Streptococcal IgA1 Proteases

2003 ◽  
Vol 71 (3) ◽  
pp. 1462-1469 ◽  
Author(s):  
Margaret R. Batten ◽  
Bernard W. Senior ◽  
Mogens Kilian ◽  
Jenny M. Woof
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Single Point ◽  
Point Mutations ◽  
Peptide Bond ◽  
Human Immunoglobulin ◽  
Single Point Mutation ◽  
Absolute Requirement ◽  
Iga1 Protease ◽  
Sequence Requirements

ABSTRACT The amino acid sequence requirements in the hinge of human immunoglobulin A1 (IgA1) for cleavage by IgA1 proteases of different species of Streptococcus were investigated. Recombinant IgA1 antibodies were generated with point mutations at proline 227 and threonine 228, the residues lying on either side of the peptide bond at which all streptococcal IgA1 proteases cleave wild-type human IgA1. The amino acid substitutions produced no major effect upon the structure of the mutant IgA1 antibodies or their functional ability to bind to Fcα receptors. However, the substitutions had a substantial effect upon sensitivity to cleavage with some streptococcal IgA1 proteases, with, in some cases, a single point mutation rendering the antibody resistant to a particular IgA1 protease. This effect was least marked with the IgA1 protease from Streptococcus pneumoniae, which showed no absolute requirement for either proline or threonine at residues 227 to 228. By contrast, the IgA1 proteases of Streptococcus oralis, Streptococcus sanguis, and Streptococcus mitis had an absolute requirement for proline at 227 but not for threonine at 228, which could be replaced by valine. There was evidence in S. mitis that proteases from different strains may have different amino acid requirements for cleavage. Remarkably, some streptococcal proteases appeared able to cleave the hinge at a distant alternative site if substitution prevented efficient cleavage of the original site. Hence, this study has identified key residues required for the recognition of the IgA1 hinge as a substrate by streptococcal IgA1 proteases, and it marks a preliminary step towards development of specific enzyme inhibitors.

Chemical structure of light chains: amino acid sequence of type K Bence-Jones proteins

1966 ◽  
Vol 166 (1003) ◽  
pp. 124-137 ◽  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sequence Data ◽  
Single Point ◽  
Structural Difference ◽  
Light Chains ◽  
Single Point Mutation ◽  
Amino Terminal ◽  
Type K ◽  
Bence Jones Proteins

Bence-Jones proteins are the light chains of the autologous myeloma globulin and are analogous to the light chains of normal human immunoglobulins. Peptide mapping has demonstrated that Bence-Jones proteins share a fixed portion of their sequence (the ‘constant’ portion) and also have a mutable part (the ‘variable’ portion). Sequence analysis and ordering of the tryptic and chymotryptic peptides has provided the tentative complete amino acid sequence of one Bence-Jones protein of antigenic type K. Comparison with partial sequence data for other type K Bence-Jones proteins has revealed many structural differences in the amino terminal half of the molecules, but only one structural difference in the carboxyl terminal half. The latter is strongly correlated with the Inv genetic factor. The points of interchange in the amino terminal half occur in clusters close to the half cystine residues and the ‘switch peptide’ (positions 102 through 105), after which the sequence becomes essentially invariant. This suggests that the major areas subject to sequence variation are part of a single topographical region which may define a portion of the antigen combining site in the light chains of antibodies. Many, but not all, the amino acid interchanges are compatible with a single point mutation. As yet, no single mutational theory suffices to explain the manifold differences in structure of the light chains. Such structural variation, however, could result from the presence of many related genes.

scholarly journals Assessing Protein-Drug Resistance Due to Mutations via a Rigidity Analysis in silico Approach

10.29007/7gnf ◽  
2020 ◽  
Author(s):  
Dylan Carpenter ◽  
Tess Thackray ◽  
Cecilia Kalthoff ◽  
Filip Jagodzinski
Keyword(s):  
Drug Resistance ◽  
Amino Acid ◽  
In Silico ◽  
Single Point ◽  
Point Mutations ◽  
Single Point Mutation ◽  
Protein Drug ◽  
Ligand Complex ◽  
Rigidity Analysis ◽  
The Impact

A mutation to the amino acid sequence of a protein can cause a biomolecule to be resistant to the intended effects of a drug. Assessing the changes of a drug’s efficacy in response to mutations via mutagenesis wet-lab experiments is prohibitively time consuming for even a single point mutation, let alone for all possible mutations. Existing approaches for inferring mutation-induced drug resistance are available, but all of them reason about mutations of residues at or very near the protein-drug interface. However, there are examples of mutations far away from the region where the ligand binds, but which nonetheless render a protein resistant to the effects of the drug. We present a proof-of-concept computational pipeline that generates in silico the set of all possible single point mutations in a protein-ligand complex. We assess drug resistance using a graph theoretic rigidity analysis approach. Unlike existing methods, we are able to assess the impact of mutations far away from the protein-drug interface. We introduce several visualizations for exploring how amino acid substitutions both near and far away from where the ligand interacts with a protein target have a stabilizing or destabilizing effect on the protein-drug complex. We discuss our analytical approach in the context of experimental data from the literature about clinically known protein-drug interactions.

Amino acid sequence requirements in the human IgAI hinge for cleavage by streptococcal IgAI proteases

2002 ◽  
Vol 30 (4) ◽  
pp. 516-518 ◽  
Author(s):  
B. W. Senior ◽  
M. R. Batten ◽  
M. Kilian ◽  
J. M. Woof
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Peptide Bond ◽  
Major Effect ◽  
Functional Abilities ◽  
Pathogenic Species ◽  
Α Chain ◽  
Sequence Requirements

All the IgA1 proteases of the different pathogenic species of Streptococcus cleave the hinge of the α chain of human IgA1 only at one proline-threonine peptide bond. In order to study the importance of these amino acids for cleavage, several hinge mutant recombinant IgA1 antibodies were constructed. The mutations were found to be without major effect upon the structure or functional abilities of the antibodies. However, they had a major effect upon their sensitivity to cleavage by some of the IgA1 proteases.

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 Mutational Analysis of Quinolone-Resistant Determining Region gyrA and parC Genes in Quinolone-Resistant ESBL-Producing E. Coli

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Hairul Aini Hamzah ◽  
Rahmatullah Sirat ◽  
Mohammed Imad A. Mustafa Mahmud ◽  
Roesnita Baharudin
Keyword(s):  
Mutational Analysis ◽  
Single Point ◽  
Point Mutations ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Single Point Mutation ◽  
Phenotypic Resistance ◽  
Drug Effectiveness ◽  
E Coli

 Introduction: Co-resistance to quinolones among extended spectrum β[1]lactamase (ESBL)-producing E. coli commonly occurs in clinical settings. Quinolones act on DNA gyrase and DNA topoisomerase enzymes, which are coded by gyrA and parC genes, thus any mutation to the genes may affect the drug effectiveness. The objective of the study was to characterize gyrA and parC genes in quinolone-resistant E. coli isolates and correlated the mutations with their phenotypic resistance. Materials and Methods: Thirty-two quinolone-resistant (QR) and six quinolone-sensitive (QS) ESBL-E. coli isolates were identified by antibiotic susceptibility and minimum inhibitory concentration tests. Bioinformatics analysis were conducted to study any mutations occurred in the genes and generate their codon compositions. Results: All the QR ESBL-E. coli isolates were identified as multidrug-resistant bacteria. A single point mutation in the quinolone resistance-determining region (QRDR) of gyrA, at codon 83, caused the substitution amino acid Ser83Leu. It is associated with a high level of resistance to nalidixic acid. However, double mutations Ser83Leu and Asp87Asn in the same region were significantly linked to higher levels of resistance to ciprofloxacin. Cumulative point mutations in gyrA and/or in parC were also correlated significantly (p<0.05) to increased resistance to ciprofloxacin. Conclusion: Together, the findings showed that the mutations in gyrA and parC genes handled the institution of intrinsic quinolone resistance in the ESBL-E. coli isolates. Thus, vigilant monitoring for emergence of new mutation in resistance genes may give an insight into dissemination of QR ESBL-E. coli in a particular region.

scholarly journals The complete amino acid sequence of chicken skeletal-muscle enolase

1986 ◽  
Vol 236 (1) ◽  
pp. 115-126 ◽  
Author(s):  
G A Russell ◽  
B Dunbar ◽  
L A Fothergill-Gilmore
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Peptide Bond ◽  
Peptide Bonds ◽  
Complete Amino Acid Sequence ◽  
Arginine Residues ◽  
Cnbr Cleavage ◽  
Yeast Enolase ◽  
Chicken Skeletal Muscle

The complete amino acid sequence of chicken skeletal-muscle enolase, comprising 433 residues, was determined. The sequence was deduced by automated sequencing of hydroxylamine-cleavage, CNBr-cleavage, o-iodosobenzoic acid-cleavage, clostripain-digest and staphylococcal-proteinase-digest fragments. The presence of several acid-labile peptide bonds and the tenacious aggregation of most CNBr-cleavage fragments meant that a commonly used sequencing strategy involving initial CNBr cleavage was unproductive. Cleavage at the single Asn-Gly peptide bond with hydroxylamine proved to be particularly useful. Comparison of the sequence of chicken enolase with the two yeast enolase isoenzyme sequences shows that the enzyme is strongly conserved, with 60% of the residues identical. The histidine and arginine residues implicated as being important for the activity of yeast enolase are conserved in the chicken enzyme. Secondary-structure predictions are analysed in an accompanying paper [Sawyer, Fothergill-Gilmore & Russell (1986) Biochem. J. 236, 127-130].

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.

Die Aminosäuresequenz des Asparaginsäure enthaltenden Mureins von Lactobacillus coryniformis und Lactobacillus cellobiosus

1967 ◽  
Vol 22 (10) ◽  
pp. 1062-1067 ◽  
Author(s):  
Roland Plapp ◽  
Otto Kandler
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Aspartic Acid ◽  
Cell Walls ◽  
Peptide Bond ◽  
Partial Hydrolysis ◽  
Cross Linking ◽  
Peptide Moiety ◽  
Lactobacillus Coryniformis ◽  
Hydrolysis Of

The amino acid sequence of the peptide moiety of the mureins of Lactobacillus coryniformis and Lactobacillus cellobiosus cell walls was determined. This was accomplished by the identification of peptides obtained after partial hydrolysis of purified cell walls and by the identification of UDP-activated murein precursors accumulated by ᴅ-cycloserine inhibition. The amino acid sequence proved to be : ʟ-ala-ᴅ-glu-ʟ-lys-ᴅ-ala for L. coryniformis and L-ala-D-glu-L-orn-D-ala for L. cellobio-.D-asp D-aspsus. Aspartic acid is involved in the cross-linking of the mureins by forming a peptide bond with the C-terminal D-alanine of an adjacent muropeptide. Glutamic acid as well as aspartic acid are present as amides.

scholarly journals Sequence specific detection of bacterial 23S ribosomal RNA by TLR13

eLife ◽  
2012 ◽  
Vol 1 ◽  
Author(s):  
Xiao-Dong Li ◽  
Zhijian J Chen
Keyword(s):  
Ribosomal Rna ◽  
Single Point ◽  
Point Mutations ◽  
Peptide Bond ◽  
Interleukin 1Β ◽  
23S Rrna ◽  
Sequence Specificity ◽  
Bacterial Rna ◽  
Microbial Infections ◽  
23S Ribosomal Rna

Toll-like receptors (TLRs) detect microbial infections and trigger innate immune responses. Among vertebrate TLRs, the role of TLR13 and its ligand are unknown. Here we show that TLR13 detects the 23S ribosomal RNA of both gram-positive and gram-negative bacteria. A sequence containing 13 nucleotides near the active site of 23S rRNA ribozyme, which catalyzes peptide bond synthesis, was both necessary and sufficient to trigger TLR13-dependent interleukin-1β production. Single point mutations within this sequence destroyed the ability of the 23S rRNA to stimulate the TLR13 pathway. Knockout of TLR13 in mice abolished the induction of interleukin-1β and other cytokines by the 23S rRNA sequence. Thus, TLR13 detects bacterial RNA with exquisite sequence specificity.

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