A sequence-specific DNA-binding factor (VF1) from Anabaena sp. strain PCC 7120 vegetative cells binds to three adjacent sites in the xisA upstream region.

摘要: Abstract A DNA-binding factor (VF1) partially purified from Anabaena sp. strain PCC 7120 vegetative cell extracts by heparin-Sepharose chromatography was found to have affinity for the xisA upstream region. The gene is required excision of an 11-kilobase element nifD during heterocyst differentiation. Previous studies sequences demonstrated that deletion this region expression heterologous promoters in cells. Mobility shift assays with a labeled 250-base-pair fragment containing binding sites revealed three distinct DNA-protein complexes. Competition experiments showed VF1 also bound rbcL and glnA genes, but fragments only single complexes mobility assays. nifH formed weak complex VF1. DNase footprinting analysis site mapped 66-base-pair repeats consensus recognition sequence ACATT.