scholarly journals Differential regulation of L1 and L2 beta-lactamase expression in Stenotrophomonas maltophilia

2002 ◽  
Vol 49 (2) ◽  
pp. 387-389 ◽  
Author(s):  
M. B. Avison
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Differential Regulation ◽  
Beta Lactamase ◽  
L1 And L2

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 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 Inactivation of mrcA gene derepresses the basal-level expression of L1 and L2  -lactamases in Stenotrophomonas maltophilia

2011 ◽  
Vol 66 (9) ◽  
pp. 2033-2037 ◽  
Author(s):  
C.-W. Lin ◽  
H.-C. Lin ◽  
Y.-W. Huang ◽  
T.-C. Chung ◽  
T.-C. Yang
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
L1 And L2 ◽  
Basal Level Expression

scholarly journals AmpDI Is Involved in Expression of the Chromosomal L1 and L2 β-Lactamases of Stenotrophomonas maltophilia

2009 ◽  
Vol 53 (7) ◽  
pp. 2902-2907 ◽  
Author(s):  
Tsuey-Ching Yang ◽  
Yi-Wei Huang ◽  
Rouh-Mei Hu ◽  
Shao-Cheng Huang ◽  
Yu-Tzu Lin
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Stenotrophomonas Maltophilia ◽  
Genomic Analysis ◽  
Comparative Genomic Analysis ◽  
Comparative Genomic ◽  
Genomic Context ◽  
One Step ◽  
L1 And L2

ABSTRACT Two ampD homologues, ampD I and ampD II, of Stenotrophomonas maltophilia have been cloned and analyzed. Comparative genomic analysis revealed that the genomic context of the ampD II genes is quite different, whereas that of the ampD I genes is more conserved in S. maltophilia strains. The ampD system of S. maltophilia is distinct from that of the Enterobacteriaceae and Pseudomonas aeruginosa in three respects. (i) AmpDI of S. maltophilia is not encoded in an ampDE operon, in contrast to what happens in the Enterobacteriaceae and P. aeruginosa. (ii) The AmpD systems of the Enterobacteriaceae and P. aeruginosa are generally involved in the regulation of ampR-linked ampC gene expression, while AmpDI of S. maltophilia is responsible for the regulation of two intrinsic β-lactamase genes, of which the L2 gene, but not the L1 gene, is linked to ampR. (iii) S. maltophilia exhibits a one-step L1 and L2 gene derepression model involving ampD I, distinct from the two- or three-step derepression of the Enterobacteriaceae and P. aeruginosa. Moreover, the ampD I and ampD II genes are constitutively expressed and not regulated by the inducer and AmpR protein, and the expression of ampD II is weaker than that of ampD I. Finally, AmpDII is not associated with the derepression of β-lactamases, and its role in S. maltophilia remains unclear.

The role of AmpR in regulation of L1 and L2 β-lactamases in Stenotrophomonas maltophilia

2009 ◽  
Vol 160 (2) ◽  
pp. 152-158 ◽  
Author(s):  
Cheng-Wen Lin ◽  
Yi-Wei Huang ◽  
Rouh-Mei Hu ◽  
Kai-Hung Chiang ◽  
Tsuey-Ching Yang
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
L1 And L2

scholarly journals Plasmid Location and Molecular Heterogeneity of the L1 and L2 β-Lactamase Genes of Stenotrophomonas maltophilia

2001 ◽  
Vol 45 (2) ◽  
pp. 413-419 ◽  
Author(s):  
Matthew B. Avison ◽  
Catherine S. Higgins ◽  
Charlotte J. von Heldreich ◽  
Peter M. Bennett ◽  
Timothy R. Walsh
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Kinetic Properties ◽  
Rrna Gene ◽  
Molecular Heterogeneity ◽  
Gram Negative Bacteria ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
L1 And L2 ◽  
Hydrolysis Of ◽  
Clinical Problems

ABSTRACT An approximately 200-kb plasmid has been purified from clinical isolates of Stenotrophomonas maltophilia. This plasmid was found in all of the 10 isolates examined and contains both the L1 and the L2 β-lactamase genes. The location of L1 andL2 on a plasmid makes it more likely that they could spread to other gram-negative bacteria, potentially causing clinical problems. Sequence analysis of the 10 L1 genes revealed three novel genes,L1c, L1d, and L1e, with 8, 12, and 20% divergence from the published strain IID 1275 L1(L1a), respectively. The most unusual L1 enzyme (L1e) displayed markedly different kinetic properties, with respect to hydrolysis of nitrocefin and imipenem, compared to those of L1a (250- and 100-fold lowerk cat/Km ratios respectively). L1c and L1d, in contrast, displayed levels of hydrolysis very similar to that of L1a. Several nonconservative amino acid differences with respect to L1a, L1b, L1c, and L1d were observed in the substrate binding-catalytic regions of L1e, and this could explain the kinetic differences. Three novel L2 genes (L2b, L2c, andL2d) were sequenced from the same isolates, and their sequences diverge from the published sequence of strain IID 1275L2 (L2a) by 4, 9, and 25%, respectively. Differences in L1 and L2 gene sequences were not accompanied by similar divergences in 16S rRNA gene sequences, for which differences of <1% were found. It is therefore apparent that the L1 and L2 genes have evolved relatively quickly, perhaps because of their presence on a plasmid.

scholarly journals AmpI Functions as an Iron Exporter To Alleviate β-Lactam-Mediated Reactive Oxygen Species Stress in Stenotrophomonas maltophilia

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Yi-Wei Huang ◽  
Hsin-Hui Huang ◽  
Kai-Hung Huang ◽  
Wei-Chien Chen ◽  
Yi-Tsung Lin ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Stenotrophomonas Maltophilia ◽  
Iron Homeostasis ◽  
Reactive Oxygen ◽  
Iron Level ◽  
Oxygen Species ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Content Type ◽  
L1 And L2

ABSTRACT Stenotrophomonas maltophilia is an organism with a remarkable capacity for drug resistance with several antibiotic resistance determinants in its genome. S. maltophilia genome codes for L1 and L2, responsible for intrinsic β-lactam resistance. The Smlt3721 gene (denoted ampI), located downstream of the L2 gene, encodes an inner membrane protein. The existence of an L2 gene-ampI operon was verified by reverse transcription-PCR (RT-PCR). For aerobically grown S. maltophilia KJ, inactivation of ampI downregulated siderophore synthesis and iron acquisition systems and upregulated the iron storage system, as demonstrated by a transcriptome assay, suggesting that AmpI is involved in iron homeostasis. Compared with the wild-type KJ, an ampI mutant had an elevated intracellular iron level, as revealed by inductively coupled plasma mass spectrometry (ICP-MS) analysis, and increased sensitivity to H2O2, verifying the role of AmpI as an iron exporter. The β-lactam stress increased the intracellular reactive oxygen species (ROS) level and induced the expression of the L1 gene and L2 gene-ampI operon. Compared to its own parental strain, the ampI mutant had reduced growth in β-lactam-containing medium, and the ampI mutant viability was improved after complementation with plasmid pAmpI in either a β-lactamase-positive or β-lactamase-negative genetic background. Collectively, upon challenge with β-lactam, the inducibly expressed L1 and L2 β-lactamases contribute to β-lactam resistance by hydrolyzing β-lactam. AmpI functions as an iron exporter participating in rapidly weakening β-lactam-mediated ROS toxicity. The L1 gene and L2 gene-ampI operon enable S. maltophilia to effectively cope with β-lactam-induced stress.

scholarly journals Induction of L1 and L2 β-Lactamase Production in Stenotrophomonas maltophilia Is Dependent on an AmpR-Type Regulator

2008 ◽  
Vol 52 (4) ◽  
pp. 1525-1528 ◽  
Author(s):  
Aki Okazaki ◽  
Matthew B. Avison
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
L2 Production ◽  
L1 And L2

ABSTRACT A divergently oriented ampR has been located upstream of bla L2 in Stenotrophomonas maltophilia. AmpR is necessary for L1 and L2 β-lactamase induction in response to β-lactam challenge, and activation of AmpR is sufficient to induce L1 and L2 production. L1 induction requires more activation of AmpR than does L2 induction.

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