Crystal structure of Mycobacterium tuberculosis Rv0760c at 1.50 A resolution, a structural homolog of Delta(5)-3-ketosteroid isomerase.

We have determined the X-ray crystal structure of the Mycobacterium tuberculosis (Mtb) gene product encoded by the open reading frame Rv0760c at 1.50 A resolution by single-wavelength anomalous dispersion (SAD) phasing of diffraction data from crystals of the selenomethionine-substituted protein. Refinement against diffraction data from the native protein resulted in R(work)=19.5% and R(free)=21.4%. The X-ray crystal structure shows that the homodimeric Rv0760c polypeptide has an alpha + beta conical barrel fold placing it among many structural neighbors of the nuclear transport factor 2 family (NTF2). This family is highly conserved in terms of structure; however the substrates and individual protein functions are diverse. The structures of native Rv0760c in several different crystal forms and Rv0760c bound to 17beta-estradiol 17-hemisuccinate (EH) have also been solved and analyzed.