Crystal structure of a MarR family transcriptional regulator protein

The multiple antibiotic resistance regulator (MarR) family of transcription factor proteins form a large group of multitasking bio-molecules in pathogenic Escherichia coli ( E. coli ). HosA is one of these MarR transcription factors reported in dozens of pathogenic E. coli with highly conserved sequence profiles. The HosA from the enteropathogenic E. coli O127:H6 (strain E2348/69), a predominantly monomeric protein, was overexpressed in E. coli and purified. The HosA protein crystals were obtained in microbatch under oil method at 4° C. The X-rays of the diffracted spots were extended to 2.21 Å resolution. The crystal belongs to the space group P 4 ₃ 22, with unit-cell parameters a = 67.16 Å, b = 67.16 Å, c = 95.66 Å and α = β = γ = 90°. In the asymmetric unit, monomeric HosA protein was crystallized and confirmed with the Matthew coefficient analysis (3.48 Å ³ Da ^-1 ). The monomeric structure is compared with previously solved structures of other homologous transcription factors. This confirmed the winged loop at the DNA binding region of the HosA protein.