Palaniappan C, Kim J K, Wisniewski M, Fay P J, Bambara R A
Department of Biochemistry & Biophysics, University of Rochester, Rochester, New York 14642, USA.
J Biol Chem. 1998 Feb 13;273(7):3808-16. doi: 10.1074/jbc.273.7.3808.
Human immunodeficiency virus reverse transcribes its single-stranded RNA genome making a DNA copy. As synthesis proceeds, the RNA is simultaneously degraded to oligomers; one of these, the polypurine tract, primes synthesis of a plus strand DNA. The viral reverse transcriptase (RT) degrades all of the non-polypurine tract oligomers. We show that unlike other DNA polymerases the retroviral RT can bind either end of an annealed RNA primer, the 5'-end for degradation and the 3'-end for synthesis. The competition between the two binding modes at any primer determines whether it will be extended or degraded. The 5'-end binding can be suppressed in at least two ways. The sequence of the primer can be such that a region at the 5'-end is unannealed or a DNA primer can be annealed just adjacent to the 5'-end of the RNA primer. This promotes binding of RT to the RNA 3'-end, allowing a primer that would normally be degraded to be extended. Implications for human immunodeficiency virus replication and antiviral therapy are discussed.
人类免疫缺陷病毒将其单链RNA基因组逆转录成DNA拷贝。随着合成过程的进行，RNA同时被降解为寡聚物；其中之一，即多聚嘌呤序列，引发正链DNA的合成。病毒逆转录酶（RT）降解所有非多聚嘌呤序列寡聚物。我们发现，与其他DNA聚合酶不同，逆转录病毒RT可以结合退火RNA引物的任何一端，5'端用于降解，3'端用于合成。在任何引物上两种结合模式之间的竞争决定了它是会被延伸还是降解。5'端结合至少可以通过两种方式被抑制。引物序列可以使得5'端的一个区域未退火，或者DNA引物可以刚好在RNA引物的5'端相邻处退火。这促进了RT与RNA 3'端的结合，使得通常会被降解的引物得以延伸。文中讨论了这对人类免疫缺陷病毒复制和抗病毒治疗的影响。
