Reverse transcriptase: Difference between revisions

As a RNA-dependent DNA Polymerase, is able to recognize the initial RNA, transcribe it to ssDNA, cleave the remaining RNA and then build up the dsDNA, to do this the protein has two active catalytic zones. Chain A has the <scene name='Reverse_transcriptase/Fingers/1'>Polymerase active site</scene> that consist of two ''finger-like'' domains, one of them recognizes the initial nucleic acid possibly by h-bonds interactions with phosphate groups of the side chains, then both domains make a conformational change closing the recognition hole to allow the second domain begin the transcription process; this change is allowed by a <scene name='Reverse_transcriptase/Flexible/1'>flexible zone</scene> between the two previous domains that is used as a common pharmaceutical target site in order to prevent this change and by this way inhibit the activity, but this one is the only zone of the Chain A that has non-conserved aminoacids giving the virus more drug resistance.  

As the same rate that the polymerization process occurs, the other active site known as the <scene name='Reverse_transcriptase/Rnase/1'>Ribonuclease H domain</scene>, cleaves the RNA releasing the ssDNA that comes again trough the Polymerase active site to become dsDNA. Finally <scene name='Reverse_transcriptase/Chainb/1'>Chain B</scene> posibly has the function to stabilize the communication between the two active sites varying the length between them in order to synchronize both functions [http://www.biochem.ucl.ac.uk/bsm/xtal/teach/repl/rt.html]

One of the principal issues about this protein comparative with the usual DNA polymerase, is lack of a correction mechanism (usually made by DNA PolIII in the DNA Pol) that increase the quota of errors, producing more mutations and by this way giving more facultative and resistance abilities to the virus.

[2] University College London. DNA Replication Enzymes <!--accessed November 28, 2009-->