A novel sequence framework (blaTEM-1G) encoding the parental TEM-1 beta-lactamase

Abstract

A novel parental bla_TEM gene (bla_TEM-1G), encoding a TEM-1 β-lactamase (pI of 5.4) produced by the uropathogenic Escherichia coli strain FMV194 was isolated from a dog. We report PCR–restriction fragment length polymorphism analysis and nucleotide sequencing of this gene. The bla_TEM-1G sequence was identical to the bla_TEM-1C gene framework in the coding and promoter (P3) regions, except for a silent G⁶⁰⁴→T mutation in the coding region. Molecular phylogenetic analysis of parental bla_TEM genes indicated two distinct groups, one comprising bla_TEM-1F and bla_TEM-2. The other group comprises bla_TEM-1C which is the probable ancestor of bla_TEM-1A, bla_TEM-1D and bla_TEM-1G. The bla_TEM-1G gene has the same framework as a gene encoding an inhibitor-resistant TEM β-lactamase produced by an E. coli strain of human origin. Thus, parental bla_TEM genes encoding β-lactamases in E. coli strains isolated from different host species, in this case human and canine, may be phylogenetically very close.