Schreiter Eric R, Rodríguez María M, Weichsel Andrzej, Montfort William R, Bonaventura Joseph
Protein Research Center, Department of Chemistry, University of Puerto Rico, Mayagüez, Puerto Rico 00681.
J Biol Chem. 2007 Jul 6;282(27):19773-80. doi: 10.1074/jbc.M701363200. Epub 2007 May 8.
S-nitrosylation is a post-translational protein modification that can alter the function of a variety of proteins. Despite the growing wealth of information that this modification may have important functional consequences, little is known about the structure of the moiety or its effect on protein tertiary structure. Here we report high-resolution x-ray crystal structures of S-nitrosylated and unmodified blackfin tuna myoglobin, which demonstrate that in vitro S-nitrosylation of this protein at the surface-exposed Cys-10 directly causes a reversible conformational change by "wedging" apart a helix and loop. Furthermore, we have demonstrated in solution and in a single crystal that reduction of the S-nitrosylated myoglobin with dithionite results in NO cleavage from the sulfur of Cys-10 and rebinding to the reduced heme iron, showing the reversibility of both the modification and the conformational changes. Finally, we report the 0.95-A structure of ferrous nitrosyl myoglobin, which provides an accurate structural view of the NO coordination geometry in the context of a globin heme pocket.
S-亚硝基化是一种蛋白质翻译后修饰，可改变多种蛋白质的功能。尽管越来越多的信息表明这种修饰可能具有重要的功能后果，但对于该部分的结构或其对蛋白质三级结构的影响却知之甚少。在此，我们报告了S-亚硝基化和未修饰的黑鳍金枪鱼肌红蛋白的高分辨率X射线晶体结构，结果表明，该蛋白质在表面暴露的半胱氨酸-10处进行体外S-亚硝基化，通过将一个螺旋和一个环“楔开”，直接导致可逆的构象变化。此外，我们在溶液和单晶中均证明，用连二亚硫酸盐还原S-亚硝基化的肌红蛋白会导致NO从半胱氨酸-10的硫上裂解，并重新结合到还原的血红素铁上，这表明修饰和构象变化都是可逆的。最后，我们报告了亚铁亚硝基肌红蛋白的0.95埃结构，该结构在球蛋白血红素口袋的背景下提供了NO配位几何的精确结构视图。
