Khan Javed A, Tao Xiao, Tong Liang
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Nat Struct Mol Biol. 2006 Jul;13(7):582-8. doi: 10.1038/nsmb1105. Epub 2006 Jun 18.
Nicotinamide phosphoribosyltransferase (NMPRTase) has a crucial role in the salvage pathway of NAD+ biosynthesis, and a potent inhibitor of NMPRTase, FK866, can reduce cellular NAD+ levels and induce apoptosis in tumors. We have determined the crystal structures at up to 2.1-A resolution of human and murine NMPRTase, alone and in complex with the reaction product nicotinamide mononucleotide or the inhibitor FK866. The structures suggest that Asp219 is a determinant of substrate specificity of NMPRTase, which is confirmed by our mutagenesis studies. FK866 is bound in a tunnel at the interface of the NMPRTase dimer, and mutations in this binding site can abolish the inhibition by FK866. Contrary to current knowledge, the structures show that FK866 should compete directly with the nicotinamide substrate. Our structural and biochemical studies provide a starting point for the development of new anticancer agents.
烟酰胺磷酸核糖转移酶（NMPRTase）在NAD +生物合成的补救途径中起关键作用，NMPRTase的强效抑制剂FK866可降低细胞内NAD +水平并诱导肿瘤细胞凋亡。我们已经确定了人源和鼠源NMPRTase的晶体结构，分辨率高达2.1埃，分别为单独状态以及与反应产物烟酰胺单核苷酸或抑制剂FK866结合的状态。这些结构表明，Asp219是NMPRTase底物特异性的决定因素，我们的诱变研究证实了这一点。FK866结合在NMPRTase二聚体界面的一个通道中，该结合位点的突变可消除FK866的抑制作用。与目前的认识相反，这些结构表明FK866应直接与烟酰胺底物竞争。我们的结构和生化研究为开发新型抗癌药物提供了一个起点。
