Ollagnier-de-Choudens Sandrine, Lascoux David, Loiseau Laurent, Barras Frédéric, Forest Eric, Fontecave Marc
Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, DBMS-CB, CEA/CNRS/Université Joseph Fourier, UMR 5047, 17 Avenue des Martyrs, 38054 Grenoble Cedex 09, France.
FEBS Lett. 2003 Dec 4;555(2):263-7. doi: 10.1016/s0014-5793(03)01244-4.
SufS is a cysteine desulfurase of the suf operon shown to be involved in iron-sulfur cluster biosynthesis under iron limitation and oxidative stress conditions. The enzyme catalyzes the conversion of L-cysteine to L-alanine and sulfide through the intermediate formation of a protein-bound cysteine persulfide in the active site. SufE, another component of the suf operon, has been previously shown to bind tightly to SufS and to drastically stimulate its cysteine desulfurase activity. Working with Escherichia coli proteins, we here demonstrate that a conserved cysteine residue in SufE at position 51 is essential for the SufS/SufE cysteine desulfurase activity. Mass spectrometry has been used to demonstrate (i). the ability of SufE to bind sulfur atoms on its cysteine 51 and (ii). the direct transfer of the sulfur atom from the cysteine persulfide of SufS to SufE. A reaction mechanism is proposed for this novel two-component cysteine desulfurase.
SufS是suf操纵子的一种半胱氨酸脱硫酶，已证明在铁限制和氧化应激条件下参与铁硫簇生物合成。该酶通过在活性位点形成蛋白质结合的半胱氨酸过硫化物中间体，催化L-半胱氨酸转化为L-丙氨酸和硫化物。suf操纵子的另一个组分SufE，先前已证明它与SufS紧密结合，并极大地刺激其半胱氨酸脱硫酶活性。我们利用大肠杆菌蛋白证明，SufE中位置51处的保守半胱氨酸残基对于SufS/SufE半胱氨酸脱硫酶活性至关重要。质谱已用于证明：（i）SufE在其半胱氨酸51上结合硫原子的能力；（ii）硫原子从SufS的半胱氨酸过硫化物直接转移到SufE。针对这种新型的双组分半胱氨酸脱硫酶提出了一种反应机制。
