Crystallization of a protein using dehydration without a precipitant.

Hypoxic response protein I (HRPI) is a protein of unknown biochemical function whose expression is very strongly upregulated in response to oxygen depletion in Mycobacterium tuberculosis. Crystals have been grown from a solution of full-length HRPI by the unusual method of dehydration without the use of precipitants. The crystals produced diffract to a maximum resolution of 2.1 A and belong to space group P4(1)2(1)2 (or P4(3)2(1)2), with unit-cell parameters a = b = 79.18, c = 37.34 A.