scholarly journals A TEM-2 beta-lactamase encoded on an active Tn1-like transposon in the genome of a clinical isolate of Stenotrophomonas maltophilia

2000 ◽  
Vol 46 (6) ◽  
pp. 879-884 ◽  
Author(s):  
M. B. Avison
Keyword(s):  
Clinical Isolate ◽  
Stenotrophomonas Maltophilia ◽  
Beta Lactamase

scholarly journals Sequence analysis and enzyme kinetics of the L2 serine beta-lactamase from Stenotrophomonas maltophilia.

1997 ◽  
Vol 41 (7) ◽  
pp. 1460-1464 ◽  
Author(s):  
T R Walsh ◽  
A P MacGowan ◽  
P M Bennett
Keyword(s):  
Amino Acids ◽  
Sequence Analysis ◽  
Clavulanic Acid ◽  
Active Site ◽  
Stenotrophomonas Maltophilia ◽  
Leader Peptide ◽  
Beta Lactamase ◽  
Class A ◽  
Cloned Gene ◽  
Kinetics Of

The L2 serine active-site beta-lactamase from Stenotrophomonas maltophilia has been classified as a clavulanic acid-sensitive cephalosporinase. The gene encoding this enzyme from S. maltophilia 1275 IID has been cloned on a 3.3-kb fragment into pK18 under the control of a Ptac promoter to generate recombinant plasmid pUB5840; when expressed in Escherichia coli, this gene confers resistance to cephalosporins and penicillins. Sequence analysis has revealed an open reading frame (ORF) of 909 bp with a GC content of 71.6%, comparable to that of the L1 metallo-beta-lactamase gene (68.4%) from the same bacterium. The ORF encodes an unmodified protein of 303 amino acids with a predicted molecular mass of 31.5 kDa, accommodating a putative leader peptide of 27 amino acids. Comparison of the amino acid sequence with those of other beta-lactamases showed it to be most closely related (54% identity) to the BLA-A beta-lactamase from Yersinia enterocolitica. Sequence identity is most obvious near the STXK active-site motif and the SDN loop motif common to all serine active-site penicillinases. Sequences outside the conserved regions display low homology with comparable regions of other class A penicillinases. Kinetics of the enzyme from the cloned gene demonstrated an increase in activity with cefotaxime but markedly less activity with imipenem than previously reported. Hence, the S. maltophilia L2 beta-lactamase is an inducible Ambler class A beta-lactamase which would account for the sensitivity to clavulanic acid.

scholarly journals AmpN-AmpG Operon Is Essential for Expression of L1 and L2 β-Lactamases in Stenotrophomonas maltophilia

2010 ◽  
Vol 54 (6) ◽  
pp. 2583-2589 ◽  
Author(s):  
Yi-Wei Huang ◽  
Cheng-Wen Lin ◽  
Rouh-Mei Hu ◽  
Yu-Tzu Lin ◽  
Tung-Ching Chung ◽  
...  
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Gene Dosage ◽  
Gram Negative Bacteria ◽  
Beta Lactamase ◽  
Gene Dosage Effect ◽  
Gram Negative ◽  
E Coli ◽  
Murein Sacculus ◽  
Lactamase Gene ◽  
L1 And L2

ABSTRACT AmpG is an inner membrane permease which transports products of murein sacculus degradation from the periplasm into the cytosol in Gram-negative bacteria. This process is linked to induction of the chromosomal ampC beta-lactamase gene in some members of the Enterobacteriaceae and in Pseudomonas aeruginosa. In this study, the ampG homologue of Stenotrophomonas maltophilia KJ was analyzed. The ampG homologue and its upstream ampN gene form an operon and are cotranscribed under the control of the promoter P ampN. Expression from P ampN was found to be independent of β-lactam exposure and ampN and ampG products. A ΔampN allele exerted a polar effect on the expression of ampG and resulted in a phenotype of null β-lactamase inducibility. Complementation assays elucidated that an intact ampN-ampG operon is essential for β-lactamase induction. Consistent with ampG of Escherichia coli, the ampN-ampG operon of S. maltophilia did not exhibit a gene dosage effect on β-lactamase expression. The AmpG permease of E. coli could complement the β-lactamase inducibility of ampN or ampG mutants of S. maltophilia, indicating that both species have the same precursor of activator ligand(s) for β-lactamase induction.

scholarly journals Aph(3′)-IIc, an Aminoglycoside Resistance Determinant from Stenotrophomonas maltophilia

2006 ◽  
Vol 51 (1) ◽  
pp. 359-360 ◽  
Author(s):  
Aki Okazaki ◽  
Matthew B. Avison
Keyword(s):  
Escherichia Coli ◽  
Clinical Isolate ◽  
Stenotrophomonas Maltophilia ◽  
Resistance Determinant ◽  
Aminoglycoside Resistance ◽  
Aminoglycoside Phosphotransferase

ABSTRACT We report the characterization of an intrinsic, chromosomally carried aph(3′)-IIc gene from Stenotrophomonas maltophilia clinical isolate K279a, encoding an aminoglycoside phosphotransferase enzyme that significantly increases MICs of kanamycin, neomycin, butirosin, and paromomycin when expressed in Escherichia coli. Disruption of aph(3′)-IIc in K279a results in decreased MICs of these drugs.

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