Crystallization and preliminary X-ray diffraction study of the histidine-containing phosphotransfer protein ZmHP1 from maize

In histidine-aspartate phosphorelays (two-component systems) involved in plant-hormone signalling, histidine-containing phosphotransfer (HPt) proteins mediate the transfer of a phosphoryl group from the sensory histidine kinase to the response regulator. The maize HPt protein ZmHP1 has been crystallized. Although ZmHP1 with an N-terminal His tag could be crystallized using sodium chloride as a precipitant, the crystals diffracted poorly to only 3.2 Å resolution. When the His tag was removed, ZmHP1 crystals were obtained using polyethylene glycol 4000 as a precipitant and the diffraction data were greatly enhanced to 2.4 Å resolution. The crystals belonged to the space group P4₁2₁2, with one ZmHP1 molecule in the asymmetric unit.