The vanC-3 vancomycin resistance gene cluster of Enterococcus flavescens CCM 439

Enterococcus flavescens CCM 439 is phenotypically similar to Enterococcus casseliflavus; it possesses intrinsic low-level resistance to vancomycin and has the VanC phenotype. The complete vanC-3 vancomycin resistance gene cluster was cloned and sequenced, and found to contain five open reading frames. These encoded five proteins that displayed a high degree of amino acid identity to the proteins of the vanC-2 cluster of E. casseliflavus. The serine racemases displayed the lowest degree of identity (97%), whereas the response regulators VanR(C-2) and VanR(C-3) were 100% identical. Long-PCR-RFLP analysis of the vanC-3 and vanC-2 gene clusters distinguished E. flavescens CCM 439 from E. casseliflavus ATCC 25788 due to the absence of a single EcoRV restriction endonuclease site from the E. flavescens gene cluster. However, the lack of nucleotide divergence between the sequences of the vanC-2 and vanC-3 clusters casts doubt on the validity of E. flavescens and E. casseliflavus being classed as distinct species.