Genetic, biochemical characterization and mutagenesis of the chromosomal class A ß-lactamase of Raoultella (formerly Klebsiella) terrigena.
Pathol Biol (Paris)
; 63(4-5): 158-63, 2015 Sep.
Article
em En
| MEDLINE
| ID: mdl-26092758
ABSTRACT
BACKGROUND:
Chromosomal class A ß-lactamases have been characterized in Raoultella ornithinolytica and Raoultella planticola. The purpose of this study was to characterize that of Raoultella terrigena. MATERIALS ANDMETHODS:
The blaTER-1 gene of R. terrigena strain ATCC33257(T) was cloned (pACter-1) and sequenced. It was then used to detect the bla gene of strains BM 85 01 095 and SB2796. The hypermutable Escherichia coli strain AB1157 mutSTn10 was transformed with pACter-1 and mutants growing on plates containing>2mg/L ceftazidime were studied. Notably, the impact of mutations only observed in the promoter region on ß-lactam resistance was assessed by site-directed mutagenesis experiments.RESULTS:
R. terrigena strains ATCC33257(T) and BM 85 01 095 had the same bla gene and deduced protein (TER-1) whereas there were 3 substitutions in those of strain SB2796 (TER-2). Class A ß-lactamases TER showed 78%, 69.9% and 38.7% identity with PLA or ORN, TEM-1 and KOXY, respectively. Compared with TEM-1, TER-1 and TER-2 showed 2 particular substitutions, Leu75Pro and Glu240Asn demonstrated to be involved in the inherent ß-lactam resistance profile of R. terrigena. TER-1 (pI of 7.6) had a high activity against penicillin G and a significantly low one against amoxicillin. Substitution G/T observed in the -35 region of the blaTER gene harbored by strains growing in the presence of≥2mg/L ceftazidime was shown to be responsible for this growth.CONCLUSION:
TER is a new class A ß-lactamase belonging to functional group 2b.Palavras-chave
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Beta-Lactamases
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Resistência beta-Lactâmica
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Enterobacteriaceae
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article