Single molecule studies show HIV-1 RT "flipping"
Dynamic binding orientations direct activity of HIV reverse transcriptase
Human immunodeficiency virus (HIV) catalyzes a series of reactions to convert its single-stranded RNA genome into double-stranded DNA for host-cell integration. This task requires the multifunctional reverse transcriptase (RT) to bind and discriminate a variety of nucleic-acid substrates such that active sites of the enzyme are correctly positioned to support RNA-directed DNA synthesis, DNA-directed DNA synthesis, and DNA-directed RNA hydrolysis. However, the mechanism by which substrates regulate the activity of the enzyme remains unclear. In their recent publication, Abbondanzieri et al. have reported distinct orientational dynamics of the RT observed on different substrates using a single-molecule assay. The enzyme adopted opposite binding orientations on duplexes containing generic DNA or RNA primers, directing its DNA synthesis or RNA hydrolysis activity, respectively. On duplexes containing the HIV polypurine tracts, RNA sequences which function as unique primers for plus-strand DNA synthesis, RT binds in both orientations and rapidly switches between the two states. Switching kinetics were regulated by cognate nucleotides and non-nucleoside RT inhibitors, a major class of anti-HIV drugs. These results indicate that the enzymatic activities of the RT are determined by its binding orientation on the substrate.
1
.
Journal Article
Publication
|
|
2
.
Xiaowei Zhuang Web Site
General Information
|
|
3
.
Stuart Le Grice Web Site
General Information
|