Analysis of Amino Acids in the b2;7–b2;8 Loop of Human Immunodeficiency Virus Type 1 Reverse Transcriptase for their Role in Virus Replication

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• 作者：Alok Mulky ; B. Christie Vu ; Joan A. Conway ; Stephen H. Hughes ; John C. Kappes
• 关键词：HIV-1 ; reverse transcriptase ; reverse transcription
• 刊名：Journal of Molecular Biology
• 出版年：2007
• 出版时间：2 February 2007
• 年：2007
• 卷：365
• 期：5
• 页码：1368-1378
• 全文大小：1190 K

文摘

The HIV-1 p51/p66 reverse transcriptase (RT) heterodimer interface comprises, in part, intermolecular interaction of the loop region between b2;-strands 7 and 8 (b2;7–b2;8 loop) in the p51 fingers subdomain with the p66 palm subdomain. In this study, for the first time in the context of infectious HIV-1 particles, we analyzed the contribution of amino acid residues (S134, I135, N136, N137, T139 and P140) in the b2;7–b2;8 loop for RT heterodimerization, enzymatic activity, and virus infectivity. Mutating asparagine 136 to alanine (N136A) reduced viral infectivity and enzyme activity dramatically. The N136A mutation appeared to destabilize the RT heterodimer and render both the p66 and p51 subunits susceptible to aberrant cleavage by the viral protease. Subunit-specific mutagenesis demonstrated that the presence of the N136A mutation in the p51 subunit alone was sufficient to cause degradation of RT within the virus particle. Alanine mutation at other residues of the b2;7–b2;8 loop did not affect either RT stability or virus infectivity significantly. None of the b2;7–b2;8 loop alanine mutations affected the sensitivity of virus to inhibition by NNRTIs. In the context of infectious virions, our results indicate a critical role of the p51 N136 residue within the b2;7–b2;8 loop for RT heterodimer stability and function. These findings suggest the interface comprising N136 in p51 and interacting residues in p66 as a possible target for rational drug design.