當(dāng)前的H1N1流感病毒對成熟的抗病毒藥物金剛胺和金剛乙胺有抵抗力,。這兩種藥物以M2蛋白為作用目標(biāo)，該蛋白是一種多功能跨膜質(zhì)子通道,。這個通道的結(jié)構(gòu)一直是一個有些爭議的話題，因為M2通道一部分的X-射線晶體結(jié)構(gòu)所顯示的電子密度相應(yīng)于微孔N-端那一部分的單一金剛胺分子,，而該通道更大一部分的溶液NMR結(jié)構(gòu)則顯示有四個金剛乙胺分子結(jié)合到螺旋體C-端朝向類脂的表面上,。
現(xiàn)在，隨著處在一個磷脂雙層中的M2通道的高分辨率結(jié)構(gòu)（該結(jié)構(gòu)利用固態(tài)NMR光譜獲得）的發(fā)表,，這個問題似乎已經(jīng)解決,。該結(jié)構(gòu)顯示金剛胺有兩個結(jié)合點：N-端通道腔中一個高親和度點和C-端蛋白表面上一個低親和度點。這項工作對于新興抗流感藥物的開發(fā)可能會有價值（這是一個重要目標(biāo),，因為2009年的季節(jié)性流感病毒對金剛胺是敏感的,，但對“達(dá)菲”（Tamiflu）卻有抵抗力），這便提出一個可能性：將來可能會出現(xiàn)多種抗藥性病毒類型,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 463, 689-692 (4 February 2010) | doi:10.1038/nature08722
Structure of the amantadine binding site of influenza M2 proton channels in lipid bilayers
Sarah D. Cady1, Klaus Schmidt-Rohr1, Jun Wang2, Cinque S. Soto2, William F. DeGrado2 & Mei Hong1
1 Department of Chemistry, Iowa State University, Ames, Iowa 50011 2, USA
2 Department of Biochemistry & Biophysics, School of Medicine, and Department of Chemistry University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, USA
The M2 protein of influenza A virus is a membrane-spanning tetrameric proton channel targeted by the antiviral drugs amantadine and rimantadine1. Resistance to these drugs has compromised their effectiveness against many influenza strains, including pandemic H1N1. A recent crystal structure of M2(22–46) showed electron densities attributed to a single amantadine in the amino-terminal half of the pore2, indicating a physical occlusion mechanism for inhibition. However, a solution NMR structure of M2(18–60) showed four rimantadines bound to the carboxy-terminal lipid-facing surface of the helices3, suggesting an allosteric mechanism. Here we show by solid-state NMR spectroscopy that two amantadine-binding sites exist in M2 in phospholipid bilayers. The high-affinity site, occupied by a single amantadine, is located in the N-terminal channel lumen, surrounded by residues mutated in amantadine-resistant viruses. Quantification of the protein–amantadine distances resulted in a 0.3??-resolution structure of the high-affinity binding site. The second, low-affinity, site was observed on the C-terminal protein surface, but only when the drug reaches high concentrations in the bilayer. The orientation and dynamics of the drug are distinct in the two sites, as shown by 2H NMR. These results indicate that amantadine physically occludes the M2 channel, thus paving the way for developing new antiviral drugs against influenza viruses. The study demonstrates the ability of solid-state NMR to elucidate small-molecule interactions with membrane proteins and determine high-resolution structures of their complexes.
