Carlson Brian L, Ballister Edward R, Skordalakes Emmanuel, King David S, Breidenbach Mark A, Gilmore Sarah A, Berger James M, Bertozzi Carolyn R
Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA 94720, USA.
J Biol Chem. 2008 Jul 18;283(29):20117-25. doi: 10.1074/jbc.M800217200. Epub 2008 Apr 4.
Type I sulfatases require an unusual co- or post-translational modification for their activity in hydrolyzing sulfate esters. In eukaryotic sulfatases, an active site cysteine residue is oxidized to the aldehyde-containing C(alpha)-formylglycine residue by the formylglycine-generating enzyme (FGE). The machinery responsible for sulfatase activation is poorly understood in prokaryotes. Here we describe the identification of a prokaryotic FGE from Mycobacterium tuberculosis. In addition, we solved the crystal structure of the Streptomyces coelicolor FGE homolog to 2.1 A resolution. The prokaryotic homolog exhibits remarkable structural similarity to human FGE, including the position of catalytic cysteine residues. Both biochemical and structural data indicate the presence of an oxidized cysteine modification in the active site that may be relevant to catalysis. In addition, we generated a mutant M. tuberculosis strain lacking FGE. Although global sulfatase activity was reduced in the mutant, a significant amount of residual sulfatase activity suggests the presence of FGE-independent sulfatases in this organism.
I型硫酸酯酶在水解硫酸酯时需要一种特殊的共翻译或翻译后修饰来发挥其活性。在真核生物硫酸酯酶中，一个活性位点的半胱氨酸残基被甲酰甘氨酸生成酶（FGE）氧化为含醛基的α-甲酰甘氨酸残基。在原核生物中，负责硫酸酯酶激活的机制尚不清楚。在此，我们描述了从结核分枝杆菌中鉴定出一种原核FGE。此外，我们解析了天蓝色链霉菌FGE同源物的晶体结构，分辨率达到2.1埃。该原核同源物与人类FGE在结构上表现出显著相似性，包括催化性半胱氨酸残基的位置。生化和结构数据均表明活性位点存在氧化半胱氨酸修饰，这可能与催化作用相关。此外，我们构建了一个缺乏FGE的结核分枝杆菌突变株。尽管该突变株的整体硫酸酯酶活性降低，但大量的残余硫酸酯酶活性表明该生物体中存在不依赖FGE的硫酸酯酶。
