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Antimicrobial Agents and Chemotherapy Nov 1990We studied the susceptibilities of relatively penicillin G-resistant and -susceptible strains of Neisseria meningitidis, as well as Neisseria lactamica and Neisseria...
We studied the susceptibilities of relatively penicillin G-resistant and -susceptible strains of Neisseria meningitidis, as well as Neisseria lactamica and Neisseria polysaccharea, to penicillin, ampicillin, and several cephalosporins. The MICs of penicillin, ampicillin, cephalothin, and cefuroxime for moderately resistant meningococci have increased two- to sixfold in relation to MICs for susceptible strains. For these strains of meningococci, N. lactamica, and N. polysaccharea, penicillin, ampicillin, cephalothin, and cefuroxime MICs for 50 and 90% of strains were similar. By genetic transformation of a penicillin-susceptible strain of N. meningitidis to low-level penicillin resistance with DNA from penicillin-resistant strains of N. meningitidis, N. lactamica, N. polysaccharea, and N. gonorrhoeae, isogenic strains with the same pattern of resistance to beta-lactams were obtained, suggesting that these commensal Neisseria spp. could be the source of meningococcal resistance genes.
Topics: Anti-Bacterial Agents; DNA, Bacterial; Drug Resistance, Microbial; Neisseria; Neisseria meningitidis; Penicillin Resistance; Phenotype; Transformation, Genetic; beta-Lactams
PubMed: 2127349
DOI: 10.1128/AAC.34.11.2269 -
Scientific Reports Sep 2019Of the ten human-restricted Neisseria species two, Neisseria meningitidis, and Neisseria gonorrhoeae, cause invasive disease: the other eight are carried...
Of the ten human-restricted Neisseria species two, Neisseria meningitidis, and Neisseria gonorrhoeae, cause invasive disease: the other eight are carried asymptomatically in the pharynx, possibly modulating meningococcal and gonococcal infections. Consequently, characterizing their diversity is important for understanding the microbiome in health and disease. Whole genome sequences from 181 Neisseria isolates were examined, including those of three well-defined species (N. meningitidis; N. gonorrhoeae; and Neisseria polysaccharea) and genomes of isolates unassigned to any species (Nspp). Sequence analysis of ribosomal genes, and a set of core (cgMLST) genes were used to infer phylogenetic relationships. Average Nucleotide Identity (ANI) and phenotypic data were used to define species clusters, and morphological and metabolic differences among them. Phylogenetic analyses identified two polyphyletic clusters (N. polysaccharea and Nspp.), while, cgMLST data grouped Nspp isolates into nine clusters and identified at least three N. polysaccharea clusters. ANI results classified Nspp into seven putative species, and also indicated at least three putative N. polysaccharea species. Electron microscopy identified morphological differences among these species. This genomic approach provided a consistent methodology for species characterization using distinct phylogenetic clusters. Seven putative novel Neisseria species were identified, confirming the importance of genomic studies in the characterization of the genus Neisseria.
Topics: DNA, Bacterial; Genome, Bacterial; Genomics; Humans; Neisseria; Phylogeny; Whole Genome Sequencing
PubMed: 31551478
DOI: 10.1038/s41598-019-50203-2 -
Journal of Microbiology and... Apr 2018Because glycosylation of aesculetin and its 6-glucoside, aesculin, enhances their biological activities and physicochemical properties, whole-cell biotransformation and...
Because glycosylation of aesculetin and its 6-glucoside, aesculin, enhances their biological activities and physicochemical properties, whole-cell biotransformation and enzymatic synthesis methodologies using amylosucrase were compared to determine the optimal production method for glycoside derivatives. High-performance liquid chromatography analysis of reaction products revealed two glycosylated products (AGG1 and AGG2) when aesculin was used as an acceptor, and three products (AG1, AG2, and AG3) when using aesculetin. The whole-cell biotransformation production yields of the major transfer products for each acceptor (AGG1 and AG1) were 85% and 25%, respectively, compared with 68% and 14% for enzymatic synthesis. These results indicate that whole-cell biotransformation is more efficient than enzymatic synthesis for the production of glycoside derivatives.
Topics: Biotransformation; Chromatography, High Pressure Liquid; Escherichia coli; Esculin; Gene Expression Regulation, Bacterial; Glucosides; Glucosyltransferases; Glycosides; Glycosylation; Neisseria; Recombinant Proteins; Time Factors; Umbelliferones
PubMed: 29724082
DOI: 10.4014/jmb.1711.11055 -
Journal of Microbiology and... Feb 2018Because glycosylation of aesculetin and its 6-glucoside, aesculin, enhances their biological activities and physicochemical properties, whole-cell biotransformation and...
Because glycosylation of aesculetin and its 6-glucoside, aesculin, enhances their biological activities and physicochemical properties, whole-cell biotransformation and enzymatic synthesis methodologies using amylosucrase were compared to determine the optimal production method for glycoside derivatives. High performance liquid chromatography analysis of reaction products revealed two glycosylated products (AGG1 and AGG2) when aesculin was used as an acceptor and three products (AG1, AG2, and AG3) when using aesculetin. The whole-cell biotransformation production yields of the major transfer products for each acceptor (AGG1 and AG1) were 85% and 25%, respectively, compared to 68% and 14% for enzymatic synthesis. These results indicate that whole-cell biotransformation is more efficient than enzymatic synthesis for the production of glycoside derivatives.
PubMed: 29385663
DOI: No ID Found -
MBio Jan 2019is quickly becoming untreatable due to its acquisition of resistance to multiple antimicrobials. It is vital that we begin to understand the mechanisms by which this is...
is quickly becoming untreatable due to its acquisition of resistance to multiple antimicrobials. It is vital that we begin to understand the mechanisms by which this is occurring. The paper by C. E. Rouquette-Loughlin, J. L. Reimche, J. T. Balthazar, V. Dhulipala, et al. (mBio 9:e02281-18, https://doi.org/10.1128/mBio.02281-18) has shown that horizontal transfer of DNA from a nasopharyngeal commensal, , has resulted in multiple sequence changes in the locus that affect both regulatory and structural regions of the MtrCDE pump, resulting in low-level azithromycin resistance. Studies such as this are increasingly important in our understanding of the movement of resistance between species and for devising strategies to overcome such events.
Topics: Anti-Bacterial Agents; Anti-Infective Agents; Bacterial Proteins; Gene Expression Regulation, Bacterial; Neisseria gonorrhoeae; Repressor Proteins
PubMed: 30647161
DOI: 10.1128/mBio.02723-18 -
Journal of Clinical Microbiology Jan 2003Neisseria meningitidis is the causative agent of meningococcal sepsis and meningitis. Neisseria polysaccharea is a nonpathogenic species. N. polysaccharea is able to use...
Neisseria meningitidis is the causative agent of meningococcal sepsis and meningitis. Neisseria polysaccharea is a nonpathogenic species. N. polysaccharea is able to use sucrose to produce amylopectin, a starch-like polysaccharide, which distinguishes it biochemically from the pathogenic species N. meningitidis. The data presented here indicate that this may be an insufficient criterion to distinguish between these two species. The nonencapsulated Neisseria strain 93246 expressed a phenotype of amylopectin production similar to that of N. polysaccharea. However, strain 93246 reacted with N. meningitidis serotype 4 and serosubtype P1.14 monoclonal antibodies and showed the N. meningitidis L1(8) lipo-oligosaccharide immunotype. Further analyses were performed on four genetic loci in strain 93246, and the results were compared with 7 N. meningitidis strains, 13 N. polysaccharea strains, and 2 N. gonorrhoeae strains. Three genetic loci, opcA, siaD, and lgt-1 in strain 93246, were the same as in N. meningitidis. Particularly, the siaD gene encoding polysialyltransferase responsible for biosynthesis of N. meningitidis group B capsule was detected in strain 93246. This siaD gene was inactivated by a frameshift mutation at the poly(C) tract, which makes strain 93246 identical to other nonencapsulated N. meningitidis strains. As expected, the ams gene encoding amylosucrase, responsible for production of amylopectin from sucrose, was detected in strain 93246 and all 13 N. polysaccharea strains but not in N. meningitidis and N. gonorrhoeae strains. These data suggest that strain 93246 is nonencapsulated N. meningitidis but has the ability to produce extracellular amylopectin from sucrose. The gene for amylopectin production in strain 93246 was likely imported from N. polysaccharea by horizontal genetic exchange. Therefore, we conclude that genetic analysis is required to complement the traditional phenotypic classification for the nonencapsulated Neisseria strains.
Topics: Amylopectin; Bacterial Proteins; Base Sequence; DNA, Bacterial; Glucosyltransferases; Humans; Molecular Sequence Data; Neisseria meningitidis; Phenotype; Polymerase Chain Reaction; Sequence Homology, Nucleic Acid; Sucrose
PubMed: 12517860
DOI: 10.1128/JCM.41.1.273-278.2003 -
Microbiology (Reading, England) Sep 2013A new generation of vaccines containing multiple protein components that aim to provide broad protection against serogroup B meningococci has been developed. One... (Comparative Study)
Comparative Study
A new generation of vaccines containing multiple protein components that aim to provide broad protection against serogroup B meningococci has been developed. One candidate, 4CMenB (4 Component MenB), has been approved by the European Medicines Agency, but is predicted to provide at most 70-80 % strain coverage; hence there is a need for second-generation vaccines that achieve higher levels of coverage. Prior knowledge of the diversity of potential protein vaccine components is a key step in vaccine design. A number of iron import systems have been targeted in meningococcal vaccine development, including the HmbR and HpuAB outer-membrane proteins, which mediate the utilization of haemoglobin or haemoglobin-haptoglobin complexes as iron sources. While the genetic diversity of HmbR has been described, little is known of the diversity of HpuAB. Using whole genome sequences deposited in a Bacterial Isolate Genome Sequence Database (BIGSDB), the prevalence and diversity of HpuAB among Neisseria were investigated. HpuAB was widely present in a range of Neisseria species whereas HmbR was mainly limited to the pathogenic species Neisseria meningitidis and Neisseria gonorrhoeae. Patterns of sequence variation in sequences from HpuAB proteins were suggestive of recombination and diversifying selection consistent with strong immune selection. HpuAB was subject to repeat-mediated phase variation in pathogenic Neisseria and the closely related non-pathogenic Neisseria species Neisseria lactamica and Neisseria polysaccharea but not in the majority of other commensal Neisseria species. These findings are consistent with HpuAB being subject to frequent genetic transfer potentially limiting the efficacy of this receptor as a vaccine candidate.
Topics: Bacterial Outer Membrane Proteins; Bacterial Proteins; Genetic Variation; Haptoglobins; Hemoglobins; Humans; Iron; Molecular Sequence Data; Neisseria; Neisseriaceae Infections; Phylogeny; Protein Conformation; Receptors, Cell Surface
PubMed: 23813677
DOI: 10.1099/mic.0.068874-0 -
Journal of Clinical Microbiology Sep 2014
Topics: Diagnostic Errors; Humans; Neisseria; Neisseriaceae Infections; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 24966359
DOI: 10.1128/JCM.01703-14 -
Journal of Bacteriology May 1997The gene for the amylosucrase from Neisseria polysaccharea (ATCC 43768) was cloned by use of a functional expression system in Escherichia coli XL1-Blue. The deduced...
The gene for the amylosucrase from Neisseria polysaccharea (ATCC 43768) was cloned by use of a functional expression system in Escherichia coli XL1-Blue. The deduced amino acid sequence of the protein has homology to the sequences of the alpha-amylase class of enzymes, with the highest similarities being found to the sequences of the trehalose synthase from Pimelobacter sp. strain R48 (17) and amylomaltase from Thermotoga maritima (11). However, the regions of highest homology within the alpha-amylase class of enzymes, which are essential for the catalytic activity, are only scarcely found in the sequence of amylosucrase. By using the enzyme isolated from culture supernatants of transformed E. coli cells, it is possible to synthesize linear alpha-1,4-glucans from sucrose, indicating that the enzyme is not capable of producing alpha-1,6-glycosidic linkages on its own.
Topics: Amino Acid Sequence; Base Sequence; Cloning, Molecular; Escherichia coli; Extracellular Space; Genes, Bacterial; Glucans; Glucosyltransferases; Molecular Sequence Data; Neisseria; Protein Sorting Signals; Sequence Homology, Amino Acid
PubMed: 9150231
DOI: 10.1128/jb.179.10.3324-3330.1997 -
Protein Science : a Publication of the... Dec 2013The amylosucrase from Neisseria polysaccharea is a transglucosidase from the GH13 family of glycoside-hydrolases that naturally catalyzes the synthesis of α-glucans...
The amylosucrase from Neisseria polysaccharea is a transglucosidase from the GH13 family of glycoside-hydrolases that naturally catalyzes the synthesis of α-glucans from the widely available donor sucrose. Interestingly, natural molecular evolution has modeled a dense hydrogen bond network at subsite -1 responsible for the specific recognition of sucrose and conversely, it has loosened interactions at the subsite +1 creating a highly promiscuous subsite +1. The residues forming these subsites are considered to be likely involved in the activity as well as the overall stability of the enzyme. To assess their role, a structure-based approach was followed to reshape the subsite -1. A strategy based on stability change predictions, using the FoldX algorithm, was considered to identify the best candidates for site-directed mutagenesis and guide the construction of a small targeted library. A miniaturized purification protocol was developed and both mutant stability and substrate promiscuity were explored. A range of 8 °C between extreme melting temperature values was observed and some variants were able to synthesize series of oligosaccharides with distributions differing from that of the parental enzyme. The crucial role of subsite -1 was thus highlighted and the biocatalysts generated can now be considered as starting points for further engineering purposes.
Topics: Amino Acid Sequence; Amino Acid Substitution; Catalytic Domain; Enzyme Stability; Evolution, Molecular; Genetic Variation; Glucans; Glucosyltransferases; Hydrogen Bonding; Models, Molecular; Mutagenesis, Site-Directed; Neisseria; Substrate Specificity; Thermodynamics
PubMed: 24115119
DOI: 10.1002/pro.2375