| Title | Experimental Phasing Using Zinc and Sulfur Anomalous Signals Measured at the Zinc Absorption Peak |
|---|---|
| Author | Sangmin Lee1,2, Min-Kyu Kim1, Chang-Jun Ji3, Jin-Won Lee3*, and Sun-Shin Cha1,2,4* |
| Address | 1Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan 426-744, Republic of Korea, 2Ocean Science and Technology School, Korea Maritime University, Pusan 606-791, Republic of Korea, 3Department of Life Science and Institute for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea, 4Department of Marine Biotechnology, University of Science and Technology, Daejeon 305-333, Republic of Korea |
| Bibliography | Journal of Microbiology, 51(5),639-643, 2013, |
| DOI | 10.1007/s12275-013-3412-2 |
| Key Words | Ferric uptake regulator, transcription regulator, crystallization, experimental phasing |
| Abstract | Iron is an essential transition metal required for bacterial growth and survival. Excess free iron can lead to the generation of reactive oxygen species that can cause severe damage to cellular functions. Cells have developed iron-sensing regulators to maintain iron homeostasis at the transcription level. The ferric uptake regulator (Fur) is an iron-responsive regulator that controls the expression of genes involved in iron homeostasis, bacterial virulence, stress resistance, and redox metabolism. Here, we report the expression, purification, crystallization, and phasing of the apo-form of Bacillus subtilis Fur (BsFur) in the absence of regulatory metal ions. Crystals were obtained by microbatch crystallization method at 295 K and diffraction data at a resolution of 2.6 Å was collected at the zinc peak wavelength (λ=1.2823 Å). Experimental phasing identified the positions of one zinc atom and four sulfur atoms of cysteine residues coordinating the zinc atom, indicating that the data contained a meaningful anomalous scattering originating from the ordered zinc-coordinating sulfur atoms, in spite of the small anomalous signals of sulfur atoms at the examined wavelength. |