In:
Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 4 ( 2007-04), p. 1365-1372
Abstract:
A novel β-lactamase gene was cloned from the whole-cell DNA of an enterobacterial Citrobacter gillenii reference strain that displayed a weak narrow-spectrum β-lactam-resistant phenotype and was expressed in Escherichia coli . It encoded a clavulanic acid-inhibited Ambler class A β-lactamase, GIL-1, with a pI value of 7.5 and a molecular mass of ca. 29 kDa. GIL-1 had the highest percent amino acid sequence identity with TEM-1 and SHV-1, 77%, and 67%, respectively, and only 46%, 31%, and 32% amino acid sequence identity with CKO-1 ( C. koseri ), CdiA1 ( C. diversus ), and SED-1 ( C. sedlaki ), respectively. The substrate profile of the purified GIL-1 was similar to that of β-lactamases TEM-1 and SHV-1. The bla GIL-1 gene was chromosomally located, as revealed by I-CeuI experiments, and was constitutively expressed at a low level in C. gillenii . No gene homologous to the regulatory ampR genes of chromosomal class C β-lactamases was found upstream of the bla GIL-1 gene, which fits the noninducibility of β-lactamase expression in C. gillenii . Rapid amplification of DNA 5′ ends analysis of the promoter region revealed putative promoter sequences that diverge from what has been identified as the consensus sequence in E. coli . The bla GIL-1 gene was part of a 5.5-kb DNA fragment bracketed by a 9-bp duplication and inserted between the d -lactate dehydrogenase gene and the ydbH genes; this DNA fragment was absent in other Citrobacter species. This work further illustrates the heterogeneity of β-lactamases in Citrobacter spp., which may indicate that the variability of Citrobacter species is greater than expected.
Type of Medium:
Online Resource
ISSN:
0066-4804
,
1098-6596
DOI:
10.1128/AAC.01152-06
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2007
detail.hit.zdb_id:
1496156-8
SSG:
12
SSG:
15,3
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