2015年6月9日訊 /生物谷BIOON/ --近日，來自澳大利亞的科學家在國際學術期刊PNAS發表了一項最新研究進展，他們通過研究發現了三種針對HIV-1逆轉錄酶的片段化抑制劑，能夠有效抑制HIV-1逆轉錄酶活性，為HIV-1預防和治療藥物開發提供了重要信息。
基於片段篩選的方法可用於發現新的活性位點或變構抑制劑以進行治療幹預。在該項研究中，研究人員利用飽和轉移磁共振和體外活性實驗的方法，發現了HIV-1逆轉錄酶的片段抑制劑，與非核苷酸類的RT抑制劑（NNRTI）和核苷酸RT抑制劑（NRTI）相比，這種片段抑制劑在化學結構和作用機制上存在很大不同。
研究人員鑑定出三種化合物能夠抑制HIV-1逆轉錄酶的RNA和DNA依賴性DNA聚合酶活性，作用濃度在微摩級別但仍保留了抑制突變型逆轉錄酶的效能，其中包括抵抗NNRTI作用的三種突變：K103N,Y181C和G190A。這些化合物還能抑制莫洛尼鼠白血病病毒逆轉錄病毒的活性，但對E.coli DNA聚合酶I的Klenow片段沒有抑制作用。
研究人員還進行了平衡態動力學分析，結果表明其中一個片段是HIV-1逆轉錄酶的競爭性抑制劑，專門作用於dNTP底物，而另一種化合物是逆轉錄酶聚合酶活性的競爭性抑制劑，專門作用於DNA模版/引物，因此這種化合物還能抑制RNase H活性。除此之外，這種dNTP競爭性逆轉錄酶抑制劑還保留了對抗NRTI抵抗型突變K65R和M184V的活性。在另一項抗病毒實驗中，研究人員證明模版/引物競爭性複合物能夠抑制HIV-1複製。
綜上所述，這項研究通過化合物篩選的方法發現三種片段具有對抗HIV-1逆轉錄酶活性的強大功能。這些片段化抑制劑的發現為HIV-1預防及治療新藥的開發提供了新的契機，具有非常重要的意義。（生物谷Bioon.com）
Identification of mechanistically distinct inhibitors of HIV-1 reverse transcriptase through fragment screening
Jennifer Laa,b,1, Catherine F. Lathama,1, Ricky N. Tinettia,c, Adam Johnsona, David Tyssena, Kelly D. Huberd, Nicolas Sluis-Cremerd, Jamie S. Simpsonb, Stephen J. Headeyb, David K. Chalmersb, and Gilda Tachedjian
Fragment-based screening methods can be used to discover novel active site or allosteric inhibitors for therapeutic intervention. Using saturation transfer difference (STD) NMR and in vitro activity assays, we have identified fragment-sized inhibitors of HIV-1 reverse transcriptase (RT) with distinct chemical scaffolds and mechanisms compared to nonnucleoside RT inhibitors (NNRTIs) and nucleoside/nucleotide RT inhibitors (NRTIs). Three compounds were found to inhibit RNA- and DNA-dependent DNA polymerase activity of HIV-1 RT in the micromolar range while retaining potency against RT variants carrying one of three major NNRTI resistance mutations: K103N, Y181C, or G190A. These compounds also inhibit Moloney murine leukemia virus RT but not the Klenow fragment of Escherichia coli DNA polymerase I. Steady-state kinetic analyses demonstrate that one of these fragments is a competitive inhibitor of HIV-1 RT with respect to deoxyribonucleoside triphosphate (dNTP) substrate, whereas a second compound is a competitive inhibitor of RT polymerase activity with respect to the DNA template/primer (T/P), and consequently also inhibits RNase H activity. The dNTP competing RT inhibitor retains activity against the NRTI-resistant mutants K65R and M184V, demonstrating a drug resistance profile distinct from the nucleotide competing RT inhibitors indolopyridone-1 (INDOPY-1) and 4-dimethylamino-6-vinylpyrimidine-1 (DAVP-1). In antiviral assays, the T/P competing compound inhibits HIV-1 replication at a step consistent with an RT inhibitor. Screening of additional structurally related compounds to the three fragments led to the discovery of molecules with improved potency against HIV-1 RT. These fragment inhibitors represent previously unidentified scaffolds for development of novel drugs for HIV-1 prevention or treatment.