Acriflavine-binding Capacity Controlled by the acrA Gene of Escherichia coli

Abstract

The acrA mutation in Escherichia coli led to a substantial increase of the acriflavine-binding capacity of the cell, whereas the related mutations acrB (gyrB) and arcC did not. Metal ions such as Na+, K+, Mg2+, Ca2+ and Al3+ effectively released the bound acriflavine, in proportion to their ionic strengths. The presence of cations, in fact, increased the survival fraction of the cells in the acriflavine-containing medium. Polymyxin B, an antibiotic which binds to membrane phospholipid, competed with acriflavine for binding sites. Cell wall digestion by treatment with lysozyme and EDTA slightly decreased the acriflavine-binding capacity. Almost no difference was observed in acriflavine-binding capacity between intact cells and cells from which lipopolysaccharide has been extracted (46.9% removed from the acrA cells and 47.4% from the acrA+ cells). Acriflavine bound to the cells was most effectively extracted by ethanol containing 1% HCl or by 2% (w/v) SDS. The difference in the acriflavine-binding capacity between the acrA and acrA+ cells was also observed in the spheroplasts. These facts indicate a relationship between the acrA gene product and the acriflavine-binding capacity of the cells.

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

“…Moreover, it has the capacity to bind on the cell wall of E. coli and the acriflavin-binding capacity is controlled by the acrA gene. A mutation of acrA leads to sensitivity not only to acriflavin but also to mitomycin C (Nakamura and Shinya, 1985). This observation may therefore suggest differences in the acrA gene and acriflavin sensitivity for 2976-1 and 10d strains compared to 09QMA277.2 and 09QMA245.2 strains.…”