Sub-millimolar zinc does not interfere with Ler binding to the LEE4 operonin vitro. Ler binding to a fragment containing the LEE4 promoter (bases -468 to +460 relative to the transcription start point) was assessed by EMSA in the presence of varied zinc acetate concentrations. Purified Ler protein at a final concentration of 0.5 μM was incubated with 100 ng DNA at room temperature for 15 min, then separated on a non-denaturing 5% polyacrylamide gel by electrophoresis at 40V for 16 hours at 4°C. When Ler was present, essentially all of the DNA was bound in a nucleoprotein complex which was not disrupted by zinc acetate at any concentration up to 100 μM, and only partially at 1000 μM (the highest concentration tested). The upper and lower arrows mark the locations of bound and unbound DNA, respectively.
Mellies et al. BMC Microbiology 2012 12:123 doi:10.1186/1471-2180-12-123