Identification of a new chromophoric substrate in the library of amino acid p-nitroanilides for continuous assay of VanX, a d,d-dipeptidase essential for vancomycin resistance

2006 ◽  
Vol 354 (1) ◽  
pp. 104-110 ◽  
Author(s):  
Ming-Lung Hsieh ◽  
Min-Jen Tseng ◽  
Ming-Chung Tseng ◽  
Yen-Ho Chu
Keyword(s):  
Amino Acid ◽  
Vancomycin Resistance ◽  
Continuous Assay

Continuous Assay for VanX, the d-Alanyl–d-Alanine Dipeptidase Required for High-Level Vancomycin Resistance

1999 ◽  
Vol 272 (1) ◽  
pp. 94-99 ◽  
Author(s):  
Jeffrey J. Brandt ◽  
Lisa L. Chatwood ◽  
Ke-Wu Yang ◽  
Michael W. Crowder
Keyword(s):  
Vancomycin Resistance ◽  
High Level ◽  
Continuous Assay

scholarly journals Peptidoglycan structure of Enterococcus faecium expressing vancomycin resistance of the VanB type

1996 ◽  
Vol 313 (3) ◽  
pp. 711-715 ◽  
Author(s):  
Danièle BILLOT-KLEIN ◽  
David SHLAES ◽  
Duncan BRYANT ◽  
David BELL ◽  
Jean van HEIJENOORT ◽  
...  
Keyword(s):  
Cell Wall ◽  
Amino Acid ◽  
Enterococcus Faecium ◽  
Amino Acid Analysis ◽  
Vancomycin Resistance ◽  
Muramic Acid ◽  
Glycopeptide Antibiotics ◽  
Cross Bridge ◽  
Peptidoglycan Structure ◽  
The Cross

Resistance to glycopeptide antibiotics in enterococci is due to the synthesis of UDP-MurNAc-tetrapeptide-D-lactate (where Mur is muramic acid) replacing the normal UDP-MurNAc-pentapeptide precursor. The peptidoglycan structures of an inducible VanB-type glycopeptide-resistant Enterococcus faecium, D366, and its constitutively resistant derivative, MT9, were determined. Using HPLC, 17 muropeptides were identified and were present regardless of whether resistance was expressed or not. The structures of 15 muropeptides were determined using MS and amino acid analysis. The cross-bridge between D-alanine and L-lysine consisted of one asparagine. No monomer pentapeptide or tetrapeptide-D-lactate could be identified. These results obtained with D366 (non-induced) and MT9 indicate that, in the absence of vancomycin, the cell wall synthetic machinery of E. faecium can process the lactate-containing precursor as efficiently as the normal pentapeptide. In contrast, the presence of subinhbitory inducing concentrations of vancomycin interfered with the synthesis of oligomers.

scholarly journals Detection of clonally related vanB2-containing Enterococcus faecium strains in two Spanish hospitals

2006 ◽  
Vol 55 (9) ◽  
pp. 1237-1243 ◽  
Author(s):  
Carmen Torres ◽  
Susanna Escobar ◽  
Aránzazu Portillo ◽  
Luis Torres ◽  
Antonio Rezusta ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gene Cluster ◽  
Intergenic Region ◽  
Enterococcus Faecium ◽  
Resistance Mechanism ◽  
Vancomycin Resistance ◽  
Pfge Pattern ◽  
Genetic Environment ◽  
Vancomycin Resistant

The aim of this study was to characterize the resistance mechanism in four clinical and five intestinal vancomycin-resistant Enterococcus faecium strains with VanB phenotype recovered from unrelated patients confined in two Spanish hospitals and to determine their clonal relationships. MIC values for vancomycin and teicoplanin were 16–32 and 0.5 μg ml−1, respectively. The mechanism of vancomycin resistance, as well as the genetic environment of the implicated gene, was analysed by PCR and sequencing. The vanB2 gene was detected in all nine E. faecium strains and the intergenic vanS B–Y B region showed the characteristic mutations of the vanB2 subtype. Two possibly related PFGE patterns, A (seven strains) and B (two strains), were distinguished among these enterococci. The vanX B–ORFC intergenic region was amplified in the nine strains and two amino acid changes were detected in the protein encoded by the vanX B gene in strains of pattern A with respect to those of pattern B. The vanB2 gene cluster was integrated into Tn5382 in all nine strains, being pbp5 gene-linked to this transposon. The ant(6′)-Ia, aph(3′)-IIIa and erm(B) genes were also detected in all of the strains. Both isolates with PFGE pattern B contained the esp gene. In summary, vanB2-containing E. faecium strains with indistinguishable PFGE patterns were recovered from seven patients from two Spanish hospitals.

scholarly journals Vancomycin-Resistant Enterococci in Humans and Imported Chickens in Japan

2002 ◽  
Vol 68 (12) ◽  
pp. 6457-6461 ◽  
Author(s):  
Yoshiyuki Ozawa ◽  
Koichi Tanimoto ◽  
Takahiro Nomura ◽  
Masao Yoshinaga ◽  
Yoshichika Arakawa ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gene Sequence ◽  
Vancomycin Resistance ◽  
Terminal Region ◽  
Resistance Determinant ◽  
Amino Acid Substitutions ◽  
Low Level ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT The phenotypes and genotypes of 22 VanA-type vancomycin-resistant enterococci that had been isolated in Japan were examined. The VanA resistance determinant was plasmid mediated in each of the 22 strains. Of the 22 strains, 8 were isolated from different patients and 11 and 3 were obtained from different samples of chickens imported from Thailand and France, respectively. Three of the strains that were isolated from patients and the 11 strains isolated from the Thai chickens showed high-level vancomycin resistance (MICs, 512 to 1,024 μg/ml) and low-level teicoplanin resistance (MICs, 0.5 to 4 μg/ml). Each of these strains had three amino acid substitutions in the N-terminal region of the deduced VanS sequence. L50 was converted to V, E54 was converted to Q, and Q69 was converted to H compared to the vanS gene sequence of Tn1546.

The staining pattern of the tropomyosin sequence is displayed in a new paracrystal

1986 ◽  
Vol 44 ◽  
pp. 150-151
Author(s):  
M.K. Lamvik ◽  
L.L. Klatt
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Staining Pattern ◽  
Banding Patterns ◽  
Mass Thickness ◽  
New Form

Tropomyosin paracrystals have been used extensively as test specimens and magnification standards due to their clear periodic banding patterns. The paracrystal type discovered by Ohtsuki1 has been of particular interest as a test of unstained specimens because of alternating bands that differ by 50% in mass thickness. While producing specimens of this type, we came across a new paracrystal form. Since this new form displays aligned tropomyosin molecules without the overlaps that are characteristic of the Ohtsuki-type paracrystal, it presents a staining pattern that corresponds to the amino acid sequence of the molecule.

Electron probe x-ray microanalysis and electron microscopy of amino acid absorption and transport by the small intestine: inhibition by chemical poisons and correlation to the elemental composition of the epithelial cells

1986 ◽  
Vol 44 ◽  
pp. 134-135
Author(s):  
A. J. Tousimis
Keyword(s):  
Small Intestine ◽  
Amino Acid ◽  
Epithelial Cells ◽  
Elemental Composition ◽  
Isotope Labeling ◽  
Structural Components ◽  
X Ray ◽  
Human Small Intestine ◽  
Transport Studies

The elemental composition of amino acids is similar to that of the major structural components of the epithelial cells of the small intestine and other tissues. Therefore, their subcellular localization and concentration measurements are not possible by x-ray microanalysis. Radioactive isotope labeling: I131-tyrosine, Se75-methionine and S35-methionine have been successfully employed in numerous absorption and transport studies. The latter two have been utilized both in vitro and vivo, with similar results in the hamster and human small intestine. Non-radioactive Selenomethionine, since its absorption/transport behavior is assumed to be the same as that of Se75- methionine and S75-methionine could serve as a compound tracer for this amino acid.

Immunoelectron microscope detection of C-type natriuretic peptide in normal human atrial tissue

1993 ◽  
Vol 51 ◽  
pp. 388-389
Author(s):  
Chi-Ming Wei ◽  
Margaret Hukee ◽  
Christopher G.A. McGregor ◽  
John C. Burnett
Keyword(s):  
Amino Acid ◽  
Natriuretic Peptide ◽  
Vascular Tone ◽  
Cardiac Tissue ◽  
Ring Structure ◽  
Terminal Amino Acid ◽  
Amino Acid Peptide ◽  
Normal Human ◽  
Terminal Amino ◽  
The Brain

C-type natriuretic peptide (CNP) is a newly identified peptide that is structurally related to atrial (ANP) and brain natriuretic peptide (BNP). CNP exists as a 22-amino acid peptide and like ANP and BNP has a 17-amino acid ring formed by a disulfide bond. Unlike these two previously identified cardiac peptides, CNP lacks the COOH-terminal amino acid extension from the ring structure. ANP, BNP and CNP decrease cardiac preload, but unlike ANP and BNP, CNP is not natriuretic. While ANP and BNP have been localized to the heart, recent investigations have failed to detect CNP mRNA in the myocardium although small concentrations of CNP are detectable in the porcine myocardium. While originally localized to the brain, recent investigations have localized CNP to endothelial cells consistent with a paracrine role for CNP in the control of vascular tone. While CNP has been detected in cardiac tissue by radioimmunoassay, no studies have demonstrated CNP localization in normal human heart by immunoelectron microscopy.

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