Crystallization and preliminary crystallographic analysis of the cell-surface alginate-binding protein Algp7 isolated from Sphingomonas sp. A1.

Sphingomonas sp. A1, a Gram-negative bacterium, directly internalizes alginate macromolecules through a mouth-like pit that is present on its cell surface. The alginate-binding protein Algp7, which was found to be localized on the cell surface, contributes to the accumulation of alginate in the pit. Algp7 was crystallized at 293 K by means of the sitting-drop vapour-diffusion method with polyethylene glycol 3350 as a crystallizing agent. Preliminary X-ray analysis showed that the Algp7 crystal belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 50.1, b = 98.0, c = 100.1 A, and that it diffracted to 2.8 A resolution.