Improving protein crystal quality by selective removal of a Ca 2+-dependent membrane-insertion loop
Lipoxygenases (LOXs) catalyze the regiospecific and stereospecific dioxygenation of polyunsaturated membrane-embedded fatty acids. A Ca 2+-dependent membrane-binding function was localized to the amino-terminal C2-like domain of 8R-lipoxygenase (8R-LOX) from the soft coral Plexaura homomalla. The 3.2 Å crystal structure of 8R-LOX and spectroscopic data suggested that Ca2+ stabilizes two membrane-insertion loops. Analysis of the protein packing contacts in the crystal lattice indicated that the conformation of one of the two loops complicated efforts to improve the resolution of the X-ray data. A deletion mutant of 8R-LOX in which the corresponding membrane-insertion loop is absent (Δ41-45:GSLOX) was engineered. Removal of the membrane-insertion loop dramatically increases the protein yield from bacterial cultures and the quality of the crystals obtained, resulting in a better than 1 Å improvement in the resolution of the diffraction data. © International Union of Crystallography 2007.
Publication Source (Journal or Book title)
Acta Crystallographica Section F: Structural Biology and Crystallization Communications
Neau, D., Gilbert, N., Bartlett, S., Dassey, A., & Newcomer, M. (2007). Improving protein crystal quality by selective removal of a Ca 2+-dependent membrane-insertion loop. Acta Crystallographica Section F: Structural Biology and Crystallization Communications, 63 (11), 972-975. https://doi.org/10.1107/S1744309107050993