scholarly journals Heterogeneity of AmpC Cephalosporinases ofHafnia alvei Clinical Isolates Expressing Inducible or Constitutive Ceftazidime Resistance Phenotypes

2000 ◽  
Vol 44 (11) ◽  
pp. 3220-3223 ◽  
Author(s):  
Delphine Girlich ◽  
Thierry Naas ◽  
Samuel Bellais ◽  
Laurent Poirel ◽  
Amal Karim ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Identity ◽  
Clinical Isolates ◽  
Hafnia Alvei ◽  
Acid Identity ◽  
Genetic Environment ◽  
Low Level ◽  
High Level

ABSTRACT Ten unrelated Hafnia alvei clinical isolates were grouped according to either their low-level and inducible cephalosporinase production or their high-level and constitutive cephalosporinase production phenotype. Their AmpC sequences shared 85 to 100% amino acid identity. The immediate genetic environment ofampC genes was conserved in H. alvei isolates but was different from that found in other ampC-possessing enterobacterial species.

scholarly journals ampG Gene of Pseudomonas aeruginosa and Its Role in β-Lactamase Expression

2010 ◽  
Vol 54 (11) ◽  
pp. 4772-4779 ◽  
Author(s):  
Ying Zhang ◽  
Qiyu Bao ◽  
Luc A. Gagnon ◽  
Ann Huletsky ◽  
Antonio Oliver ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Transmembrane Protein ◽  
Amino Acid Identity ◽  
Clinical Isolates ◽  
Signal Molecules ◽  
Carbonyl Cyanide ◽  
Increased Sensitivity ◽  
Potential Strategy ◽  
High Level

ABSTRACT In enterobacteria, the ampG gene encodes a transmembrane protein (permease) that transports 1,6-GlcNAc-anhydro-MurNAc and the 1,6-GlcNAc-anhydro-MurNAc peptide from the periplasm to the cytoplasm, which serve as signal molecules for the induction of ampC β-lactamase. The role of AmpG as a transporter is also essential for cell wall recycling. Pseudomonas aeruginosa carries two AmpG homologues, AmpG (PA4393) and AmpGh1 (PA4218), with 45 and 41% amino acid sequence identity, respectively, to Escherichia coli AmpG, while the two homologues share only 19% amino acid identity. In P. aeruginosa strains PAO1 and PAK, inactivation of ampG drastically repressed the intrinsic β-lactam resistance while ampGh1 deletion had little effect on the resistance. Further, deletion of ampG in an ampD-null mutant abolished the high-level β-lactam resistance that is associated with the loss of AmpD activity. The cloned ampG gene is able to complement both the P. aeruginosa and the E. coli ampG mutants, while that of ampGh1 failed to do so, suggesting that PA4393 encodes the only functional AmpG protein in P. aeruginosa. We also demonstrate that the function of AmpG in laboratory strains of P. aeruginosa can effectively be inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP), causing an increased sensitivity to β-lactams among laboratory as well as clinical isolates of P. aeruginosa. Our results suggest that inhibition of the AmpG activity is a potential strategy for enhancing the efficacy of β-lactams against P. aeruginosa, which carries inducible chromosomal ampC, especially in AmpC-hyperproducing clinical isolates.

scholarly journals Characterization of a Naturally Occurring Class D β-Lactamase from Achromobacter xylosoxidans

2008 ◽  
Vol 52 (6) ◽  
pp. 1952-1956 ◽  
Author(s):  
Yohei Doi ◽  
Laurent Poirel ◽  
David L. Paterson ◽  
Patrice Nordmann
Keyword(s):  
Amino Acid ◽  
Amino Acid Identity ◽  
Burkholderia Cenocepacia ◽  
Achromobacter Xylosoxidans ◽  
Acid Identity ◽  
Low Level ◽  
Narrow Spectrum ◽  
Naturally Occurring ◽  
Class D

ABSTRACT A chromosomally encoded class D β-lactamase, OXA-114, was characterized from Achromobacter xylosoxidans strain CIP69598. β-Lactamase OXA-114 shared 56% amino acid identity with the naturally occurring class D β-lactamase of Burkholderia cenocepacia and 42% identity with the acquired oxacillinases OXA-9 and OXA-18. OXA-114 has a narrow-spectrum hydrolysis profile, although it includes imipenem, at a very low level. PCR and sequencing revealed that bla OXA-114-like genes were identified in all A. xylosoxidans strains tested (n = 5), indicating that this β-lactamase is naturally occurring in that species. Induction experiments with imipenem and cefoxitin did not show inducibility of bla OXA-114 expression.

scholarly journals Cloning of a Novel Gene for Quinolone Resistance from a Transferable Plasmid in Shigella flexneri 2b

2005 ◽  
Vol 49 (2) ◽  
pp. 801-803 ◽  
Author(s):  
Mami Hata ◽  
Masahiro Suzuki ◽  
Masakado Matsumoto ◽  
Masao Takahashi ◽  
Katsuhiko Sato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Clinical Isolate ◽  
Shigella Flexneri ◽  
Amino Acid Identity ◽  
Quinolone Resistance ◽  
Acid Identity ◽  
Low Level ◽  
Novel Gene ◽  
Level Resistance

ABSTRACT A novel gene for quinolone resistance was cloned from a transferable plasmid carried by a clinical isolate of Shigella flexneri 2b that was resistant to fluoroquinolones. The plasmid conferred low-level resistance to quinolones on Escherichia coli HB101. The protein encoded by the gene showed 59% amino acid identity with Qnr.

scholarly journals Interference between avian endogenous ev/J 4.1 and exogenous ALV-J retroviral envelopes

2003 ◽  
Vol 84 (12) ◽  
pp. 3233-3238 ◽  
Author(s):  
Caroline Denesvre ◽  
Denis Soubieux ◽  
Gaelle Pin ◽  
Dominique Hue ◽  
Ginette Dambrine
Keyword(s):  
Amino Acid ◽  
Envelope Protein ◽  
Avian Leukosis Virus ◽  
Amino Acid Identity ◽  
Acid Identity ◽  
New Family ◽  
Endogenous Sequence ◽  
High Level

A new family of avian retroviral endogenous sequences designated ev/J or EAV-HP has been identified recently. Here an additional avian ev/J 4.1 endogenous sequence, ev/J 4.1 Rb, is reported. ev/J 4.1 Rb has the most extensive amino acid identity ever described for an endogenous envelope protein with the ALV-J avian leukosis virus. Here, we also demonstrate that ev/J 4.1 Rb functionally pseudotypes murine leukaemia virions and leads to a complete reciprocal interference with ALV-J envelopes. This is the first demonstration of such a high level of envelope interference between endogenous and exogenous avian retroviruses. Our results provide additional clues on the co-evolution of retroviral sequences among vertebrates.

scholarly journals Molecular and Biochemical Characterization of a Novel Class A β-Lactamase (HER-1) from Escherichia hermannii

2003 ◽  
Vol 47 (8) ◽  
pp. 2669-2673 ◽  
Author(s):  
Anne Beauchef-Havard ◽  
Guillaume Arlet ◽  
Valerie Gautier ◽  
Roger Labia ◽  
Patrick Grimont ◽  
...  
Keyword(s):  
Amino Acid ◽  
Broad Spectrum ◽  
Aeromonas Hydrophila ◽  
Biochemical Characterization ◽  
Amino Acid Identity ◽  
Acid Identity ◽  
Low Level ◽  
Class A ◽  
Moderate Susceptibility

ABSTRACT Escherichia hermannii showed a low level of resistance to amoxicillin and ticarcillin, reversed by clavulanate, and a moderate susceptibility to piperacillin but was susceptible to all cephalosporins. A bla gene was cloned and encoded a typical class A β-lactamase (HER-1, pI 7.5), which shares 45, 44, 41, and 40% amino acid identity with other β-lactamases, AER-1 from Aeromonas hydrophila, MAL-1/Cko-1 from Citrobacter koseri, and TEM-1 and LEN-1, respectively. No ampR gene was detected. Only penicillins were efficiently hydrolyzed, and no hydrolysis was observed for cefuroxime and broad-spectrum cephalosporins. Sequencing of the bla gene in 12 other strains showed 98 to 100% identity with bla HER-1.

scholarly journals Coproduction of 16S rRNA Methyltransferase RmtD or RmtG with KPC-2 and CTX-M Group Extended-Spectrum β-Lactamases in Klebsiella pneumoniae

2013 ◽  
Vol 57 (5) ◽  
pp. 2397-2400 ◽  
Author(s):  
Maria Fernanda C. Bueno ◽  
Gabriela R. Francisco ◽  
Jessica A. O'Hara ◽  
Doroti de Oliveira Garcia ◽  
Yohei Doi
Keyword(s):  
Amino Acid ◽  
16S Rrna ◽  
Klebsiella Pneumoniae ◽  
Amino Acid Identity ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
Acid Identity ◽  
Paulo State ◽  
Extended Spectrum ◽  
High Level

ABSTRACTEightKlebsiella pneumoniaeclinical strains with high-level aminoglycoside resistance were collected from eight hospitals in São Paulo State, Brazil, in 2010 and 2011. Three of them produced an RmtD group 16S rRNA methyltransferase, RmtD1 or RmtD2. Five strains were found to produce a novel 16S rRNA methyltransferase, designated RmtG, which shared 57 to 58% amino acid identity with RmtD1 and RmtD2. Seven strains coproduced KPC-2 with or without various CTX-M group extended-spectrum β-lactamases, while the remaining strain coproduced CTX-M-2.

Mutations in aarE, the ubiA Homolog of Providencia stuartii, Result in High-Level Aminoglycoside Resistance and Reduced Expression of the Chromosomal Aminoglycoside 2′-N-Acetyltransferase

1998 ◽  
Vol 42 (4) ◽  
pp. 959-962 ◽  
Author(s):  
Michael R. Paradise ◽  
Gregory Cook ◽  
Robert K. Poole ◽  
Philip N. Rather
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Identity ◽  
Second Step ◽  
Aminoglycoside Resistance ◽  
Acid Identity ◽  
E Coli ◽  
Small Colony ◽  
Providencia Stuartii ◽  
High Level

ABSTRACT The aarE1 allele was identified on the basis of the resulting phenotype of increased aminoglycoside resistance. TheaarE1 mutation also resulted in a small-colony phenotype and decreased levels of aac(2′)-Ia mRNA. The deduced AarE gene product displayed 61% amino acid identity to theEscherichia coli UbiA protein, an octaprenyltransferase required for the second step of ubiquinone biosynthesis. Complementation experiments in both Providencia stuartiiand E. coli demonstrated that aarE andubiA are functionally equivalent.

scholarly journals Biochemical-Genetic Characterization and Distribution of OXA-22, a Chromosomal and Inducible Class D β-Lactamase fromRalstonia (Pseudomonas)pickettii

2000 ◽  
Vol 44 (8) ◽  
pp. 2201-2204 ◽  
Author(s):  
Patrice Nordmann ◽  
Laurent Poirel ◽  
Maryline Kubina ◽  
Anne Casetta ◽  
Thierry Naas
Keyword(s):  
Amino Acid ◽  
Genomic Dna ◽  
Genetic Characterization ◽  
Amino Acid Identity ◽  
Clinical Isolates ◽  
Acid Identity ◽  
Ralstonia Pickettii ◽  
Class D ◽  
Biochemical Genetic ◽  
Lactamase Gene

ABSTRACT From genomic DNA of Ralstonia pickettii isolate PIC-1, a β-lactamase gene was cloned that encodes the oxacillinase OXA-22. It differs from known oxacillinases, being most closely related to OXA-9 (38% amino acid identity). The hydrolytic spectrum of OXA-22 is limited mostly to benzylpenicillin, cloxacillin, and restricted-spectrum cephalosporins. OXA-22-like genes were identified as single chromosomal copies in five other R. pickettii clinical isolates. The expression of OXA-22-like β-lactamases was inducible in R. pickettii.

scholarly journals Fluoroquinolone Resistance in Clinical Isolates ofStreptococcus pneumoniae: Contributions of Type II Topoisomerase Mutations and Efflux to Levels of Resistance

2000 ◽  
Vol 44 (11) ◽  
pp. 3049-3054 ◽  
Author(s):  
Darrin J. Bast ◽  
Donald E. Low ◽  
Carla L. Duncan ◽  
Laurie Kilburn ◽  
Lionel A. Mandell ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Amino Acid Substitutions ◽  
Type Ii ◽  
Low Level ◽  
High Level ◽  
The Impact ◽  
Level Resistance

ABSTRACT We report on amino acid substitutions in the quinolone resistance-determining region of type II topisomerases and the prevalence of reserpine-inhibited efflux for 70 clinical isolates ofS. pneumoniae for which the ciprofloxacin MIC is ≥4 μg/ml and 28 isolates for which the ciprofloxacin MIC is ≤2 μg/ml. The amino acid substitutions in ParC conferring low-level resistance (MICs, 4 to 8 μg/ml) included Phe, Tyr, and Ala for Ser-79; Asn, Ala, Gly, Tyr, and Val for Asp-83; Asn for Asp-78; and Pro for Ala-115. Isolates with intermediate-level (MICs, 16 to 32 μg/ml) and high-level (MICs, 64 μg/ml) resistance harbored substitutions of Phe and Tyr for Ser-79 or Asn and Ala for Asp-83 in ParC and an additional substitution in GyrA which included either Glu-85-Lys (Gly) or Ser-81-Phe (Tyr). Glu-85-Lys was found exclusively in isolates with high-level resistance. Efflux contributed primarily to low-level resistance in isolates with or without an amino acid substitution in ParC. The impact of amino acid substitutions in ParE was minimal, and no substitutions in GyrB were identified.

scholarly journals Amino acid identity at one position within the α1 helix of both the histidine kinase and the response regulator of the WalRK and PhoPR two-component systems plays a crucial role in the specificity of phosphotransfer

Microbiology ◽  
2010 ◽  
Vol 156 (6) ◽  
pp. 1848-1859 ◽  
Author(s):  
Inga Jende ◽  
Kottayil I. Varughese ◽  
Kevin M. Devine
Keyword(s):  
Amino Acid ◽  
Response Regulator ◽  
Amino Acid Identity ◽  
Response Regulators ◽  
Acid Identity ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems ◽  
Interacting Surfaces ◽  
High Level

Two-component systems usually function as cognate pairs, thereby ensuring an appropriate response to the detected signal. The ability to exclusively phosphorylate a partner protein, often in the presence of many competing homologous substrates, demonstrates a high level of specificity that must derive from the interacting surfaces of the two-component system. Here, we identify positions within the histidine kinases and response regulators of the WalRK and PhoPR two-component systems of Bacillus subtilis that make a major contribution to the specificity of phosphotransfer. Changing the identity of the amino acid at position 11 within the α1 helix of WalK and at position 17 within the α1 helix of PhoP altered discrimination and allowed phosphotransfer to occur with the non-cognate partner. Changing amino acids at additional positions of the WalK kinase increased phosphotransfer, while changes at additional positions in PhoP only had an effect in the presence of the change at position 17. The importance of amino acid identity at these two positions is supported by the fact that the amino acid combinations of Ile and Ser in WalRK, and Leu and Gly in PhoPR, are very highly conserved among orthologues, while modelling indicates that these amino acid pairs are juxtaposed in the WalRK and PhoPR complexes.

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