Huang Qingqiu, Hong Xinguo, Hao Quan
MacCHESS at the Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853, USA.
FEBS Lett. 2008 Apr 30;582(10):1431-6. doi: 10.1016/j.febslet.2008.03.028. Epub 2008 Mar 28.
SNAP-25 has a cysteine cluster located at its linker domain. In vivo, the cysteine residues in this cluster can be palmitoylated, and the hydrophobic palmitate molecules can target SNAP-25 to the presynaptic membrane. Here, we report that the SNAP-25a expressed in Escherichia coli is also an iron-sulfur protein binding an iron-sulfur cluster using the cysteine residues in its cysteine cluster. Therefore, SNAP-25a uses the same cysteine residues to bind two different prosthetic groups (iron-sulfur cluster and palmitate). Because the binding sites of these two prosthetic groups overlap, we suggest that these two modifications occur at different times, and probably at different places in the cell.
SNAP-25在其连接结构域有一个半胱氨酸簇。在体内，该簇中的半胱氨酸残基可被棕榈酰化，疏水性的棕榈酸分子可将SNAP-25靶向突触前膜。在此，我们报道在大肠杆菌中表达的SNAP-25a也是一种铁硫蛋白，它利用其半胱氨酸簇中的半胱氨酸残基结合一个铁硫簇。因此，SNAP-25a利用相同的半胱氨酸残基结合两种不同的辅基（铁硫簇和棕榈酸）。由于这两种辅基的结合位点重叠，我们认为这两种修饰发生在不同的时间，可能也发生在细胞内的不同位置。
