Expression, purification and function of cysteine desulfurase from Sulfobacillus acidophilus TPY isolated from deep-sea hydrothermal vent.

Abstract

The cysteine desulfurase (SufS) gene of Sulfobacillus acidophilus TPY, a Gram-positive bacterium isolated from deep-sea hydrothermal vent, was cloned and over-expressed in E. coli BL21. The recombinant SufS protein was purified by one-step affinity chromatography. The TPY SufS contained a well conserved motif RXGHHCA as found in that of other microorganisms, suggesting that it belonged to group II of cysteine desulfurase family. The recombinant TPY SufS could catalyze the conversion of l-cysteine to l-alanine and produce persulfide, and the enzyme activity was 95μ/μL of sulfur ion per minute. The growth of E. coli BL21 was promoted by over-expressing TPY SufS in vivo or by directly adding recombinantTPY SufS in the medium (4.3-4.5×108cells/mL vs. 3.2-3.5×108cells/mL). Furthermore, the highest cell density of E. coli BL21 when the TPY SufS was over-expressed was about 3.5 times that of the control groups in the presence of sodium thiosulfate. These results indicate that the SUF system as the only assembly system of iron-sulfur clusters not only has significant roles in survival of S. acidophilus TPY, but also might be important for combating with high content of sulfide.