FolX from Pseudomonas aeruginosa is octameric in both crystal and solution

► Structural investigation of FolX from Pseudomonas aeruginosa. ► A combination of AUC and SAXS allows the X-ray structure to be 'improved'. ► FolX is shown an octamer in both crystal and in solution. ► A network of 16 hydrogen bonds and 8 salt bridges provide octamer stability.